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TEXT-BOOK 


OF 





ZOOLOGY 


193 


FOR SCHOOLS AND COLLEGES. 



BY 


H. ALLEYNE NICHOLSOX, 

M.D., D. Sc., M.A., Pii.D., F.R.S.E., F.G.S., Etc., 

PROFESSOR OF NATURAL niSTORY AND BOTANY IN UNIVERSITY COLLEGE, TORONTO J 
formerly lecturer on natural history in the medical school of Edin¬ 
burgh; AUTHOR OF MANUAL OF ZOOLOGY FOR THE USE OF STUDENTS,” 

“TEXT-BOOK OF GEOLOGY,” “INTRODUCTORY TEXT-BOOK OF 
ZOOLOGY,” “GEOLOGY OF CUMBERLAND AND 
WESTMORELAND,” ETC., ETC. 


> 



NEW YORK: 

D. APPLETON AND COMPANY, 

1, 3, and 5 BOND STREET. 

1883 . 



Entered, according to Act of Congress, in the year 1871, by 
D. APPLETON & CO., 

In the Office of the Librarian of Congress, at Washington. 



In bringing out a Text-book of Natural History, intended 
mainly for the use of schools, there are a few remarks which 
it may be as well to make by way of preface, if only to ex¬ 
plain the principles upon which the work has been written. 

In the first place, more space has been devoted, compara¬ 
tively speaking, to the Invertebrate Animals than has usually 
been the case in introductory works, upon the belief that any 
practical Zoological work likely to be undertaken by young 
students will certainly be in connection with these rather 
than with the Vertebrate Animals. 

Secondly, the Author has devoted considerable space to a 
discussion of the principles of Zoological classification, be¬ 
lieving that it is of paramount importance that the student 
should have a clear idea of the principles upon which the 
Animal Kingdom has been systematically divided. At the 
same time, the introductory portion of the work is more 
especially intended for the teacher; and there is much in it 
that the learner may perhaps hardly understand till he has 
arrived at some clear idea of Natural History as a whole. 

Thirdly, while the Author trusts that the style of the 
work will be found clear and intelligible, he does not believe 
in the existence of any royal road to learning in Natural 
History, any more than in any other department of human 
knowledge. If Natural History is ever to be taught in 



IV 


PREFACE. 


schools, with any satisfaction to the teacher, or any profit to 
the learner, it must be taught as systematically and as un¬ 
flinchingly as Mathematics and Greek have been taught for 
many generations. The Author is one of those who believe 
that the time is now approaching, if it be not already here, 
when the Natural Sciences will take their true place in school 
education, as second to no other branch of knowledge, either 
as regards their intrinsic value and interest, or regarded mere¬ 
ly as a means of developing the mental powers. Acting upon 
this belief, the Author has, therefore, treated his subject in a 
purely scientific spirit; and, while avoiding as much as pos¬ 
sible the use of technicalities, he has not endeavored to lend 
his subject any false glitter or embellishment; firmly believ¬ 
ing that there is even a certain mental training involved in 
the recognition that a strictly scientific description is not 
without its own charms and beauties. While the use of tech¬ 
nical terms has been as far as possible restricted, it is believed 
that an explanation of every unavoidable term will be found 
in the glossary, or is appended in the text. 

Lastly, the illustrations, with few exceptions, have been 
drawn on the wood by the Author, and he has thought it wise 
to wholly eschew the use of pictorial illustrations, as unneces¬ 
sary in a scientific work, however elementary it may be. 


table of contents 


INTRODUCTION. 

Definition of Biology and Zoology—Characters of dead and unorganized bodies—Characters 
of living and organized bodies—Differences between animals and plants—Principles of 
Zoological classification—The great Physiological Functions—Homology and Analogy— 
General Divisions of the Animal Kingdom—Invertebrata and Yertebrata, . Pages 1-24 

CHAPTER I. 

General characters of the Protozoa—Classification of the Protozoa—Gregarinida?, - p. 25-28 

CHAPTER II. 

General characters and orders of the Rhizopoda—Anatomy of the Amcebea—Foraminifera— 
Affinities—distribution of the Foraminifera in Space and in Time—Radiolaria—Acan- 
thometne—Polycystina—Thallassicollida—Spongida—Structure of a Sponge—Reproduc¬ 
tion of Spongilla—Distribution of Sponges in space,.p. 29-44 

CHAPTER III. 

General characters of the Infusoria—Anatomy of Paramcccium—Structure of Epistylis— 
Orders of Infusoria—Distribution of Infusoria in space—Tabular view of the divisions 
of the Protozoa,.p. 45-49 


CHAPTER IY. 

General characters of the Ccelenterata—Divisions of the Ccclcntcrata—General characters of 
the Ilydrozoa—General terminology of the Hydrozoa,.p. 50-56 

CHAPTER Y. 

Divisions of the Hydrozoa—Hydroida—Hydrida—Anatomy of Hydra—Corvnida—Repro¬ 
duction in the Corynida and in the Hydroid Zoophytes generally—Alternation of gen¬ 
erations—Sertularida—Campanularida,.p. 57-G9 

CHAPTER YI. 

Siphonophora or Oceanic Hydrozoa—Calycophoridse—Physophoridae, . . . p. 70-73 

CHAPTER VII. 

Discophora or Medusidae—Structure of Naked-eyed Medusae—Their nature, . p. 74-77 




VI 


TABLE OF CONTENTS. 


CHAPTER VIII. 

Lucernarida—Hidden-eyed Medusae—Development of Lucernarida—Rhizostomidae—Grap- 
tolitidae, ..Pages 78-83 


CHAPTER IX. 

General characters of the Actinozoa—Zoantharia—Anatomy of a Sea-Anemone—Zoantharia 
Sclerodermata—Sclerodermic and Sclerobasic Corals—Coral-reefs—Zoantharia Sclero- 
basica—Alcyonaria—Gorgonidae—Red Coral—Rugose Corals—Ctenophora—Anatomy of 
Pleurobrachia—Tabular view of the divisions of the Ccelenterata, . . . p. 84-94 

CHAPTER X. 

General characters of the Annuloida—General characters of the Echinodermata—Divisions 
of the Echinodermata—Echinoidea—Anatomy of Echinus—Asteroidea—Ophiuroidea— 
Crinoidea—Cystoidea and Blastoidea—Holothuroidea,.p. 95-107 


CHAPTER XL 

General characters of the Scolecida—Divisions of the Scolecida—Taeniada—Development of 
a Tape-worm—Cystic worms—Trematoda—Turbellaria—Acanthocephala—Gordiacea— 
Nematoda—Rotifera—Tabular view of the divisions of the Annuloida, . p. 108-117 


CHAPTER XII. 

General characters of the Annulosa—Characters of the Anarthropoda—Gephyrea—Annelida 
—Divisions of the Annelida—Ilirudinea—Oligochaeta—Tubicola—Errantia, p. 118-125 

CHAPTER XIII. 

General characters of the Arthropoda—Divisions of the Arthropoda, . . . p. 126,127 


CHAPTER XIV. 

General characters of the Crustacea—Decapoda—Macrura—Anomura—Brachyura—Isopoda 
—Merostomata—Trilobita—Cladocera, Copepoda, and Ostracoda—Cirripedia—Appendix 
of the remaining orders of Crustaceans,.p. 128-138 


CHAPTER XV. 


General characters of the Arachnida—Podosomata—Acarina—Pedipalpi—Araneida, 

p. 139-143 


CHAPTER XVI. 

> f' 

General characters of the Myriapoda—Centipedes—Millipedes 


p. 144,145 


CHAPTER XVII. 

General characters and anatomy of Insects—Metamorphoses of Insects, . . p. 143-152 


CHAPTER XVIII. 

Orders of Insects—Anoplura—Mallophaga—Thysanura—Hemiptera—Orthoptera—Xeurop- 
tera—Aphaniptera—Diptera—Lepidoptera— Hymenoptera—Strepsiptera—Coleoptera— 
Tabular view of the divisions of the sub-kingdom Annulosa, . . . p. 153-163 



TABLE OF CONTENTS. 


Vll 


CHAPTER XIX. 

General characters of the Mollusca— Primary divisions of the Mollusca, . Pages 164-167 


CHAPTER XX. 

Molluscoida—General characters of the Polyzoa—General characters of the Tunicata—Gen¬ 
eral characters of the Brachiopoda, .p. 168-175 


CHAPTER XXI. 

Classes of the Mollusca Proper—General characters of the Lamellibranchiata—General char¬ 
acters of the Gasteropoda—Nudibranchiata—Ileteropoda—Air-breathing Gasteropods— 
Pteropoda,.p. 176-186 


CHAPTER XXII. 

General characters of the Cephalopoda—Reproductive process in the Cuttle-fishes—Shell of 
the Cephalopoda—Dibranchiata—Tetrabrancliiata—Orthocerata—Ammonites—Tabular 
view of the main divisions of the Mollusca,.p. 187-194 

CHAPTER XXIII. 

General characters of the Vertebrata —Skeleton of Vertebrates—Structure of a Vertebra— 
Vertebral column—Limbs of Vertebrates—Digestive system—Circulatory system—Re¬ 
spiratory system—Nervous system—Reproduction—Primary divisions—Ichthyopsida— 
Sauropsida—Mammalia,.p. 195-2C5 


CHAPTER XXIV. 

General characters of the Fishes—Scales—Endoskeleton—Limbs—Tail—Digestive system— 
Circulation—Respiration—Nervous system—Organs of hearing and smell—Reproduc¬ 
tion, . .p. 206-213 


CHAPTER XXV. 


Orders of Fishes—Pliaryngobranchii—Marsipobranchii—Teleostei—Sub-orders of the Tele- 
ostei—Ganoidei—Elasmobranchii—Sub-orders of the Elasmobranchii—Dipnoi, 

p. 214-224 


CHAPTER XXVI. 

General characters of the Amphibia—Orders of the Amphibia—Ophiomorpha—Urodela— 
Anoura—Labyrinthodoutia,.p. 225-233 


CHAPTER XXVII. 

General characters of the Reptilia—Circulatory and Respiratory systems—Divisions, 

p. 234-237 


CHAPTER XXVIII. 

Orders of Reptilia—Chclonia—Ophidia—Lacertilia—Crocodilia—Ichthyopterygia—Saurop- 
terygia—Pterosauria,.p. 238-252 


CHAPTER XXIX. 

General characters of the Class Aves—Feathers—Vertebral column—Anterior extremity 
and pectoral arch—posterior extremity and pelvic arch—Digestive system—Respira- 









TABLE OF CONTENTS. 


tion—Circulatory system—Nervous system—Organs of the Senses—Migrations of 
Birds,.Pages 253-264 


CHAPTER XXX. 

Divisions of Aves — Natatores — Grallatores—Cursores—Easores—Scansores—Insessores— 
Raptores—Saururae,.p. 265-279 


CHAPTER XXXI. 

General characters of the Class Mammalia—Skeleton—Teeth—Dental formula—Digestive 
system—Heart—Lungs—Nervous system—Integumentary appendages—Development 
—Primary divisions,.p. 280-287 


CHAPTER XXXII. 

Orders of Mammalia—Monotremata—Marsupialia—Edentata—Sirenia—Cetacea—Ungulata 
—Ilyracoidea—Proboscidea—Carnivora—Rodentia—Cheiroptera — Insectivora — Quad- 
rumana—Biman a,.p. 288-320 








LIST OF ILLUSTRATIONS. 


Fra. 


PAGH 


1. Diagram representing Transverse Sections of tlie Invertebrata and 

Vertebrata, . ...... 

2. Gregarina of the Earth-worm, ...... 

3. Morphology of Rhizopoda, ...... 

4. Morphology of Foraminifera , ..... 

5. Nummulites Icevigatus , ....... 

6. Acanthometra and Haliomma, ..... 

7. Morphology of Thalassicollida, ...... 

8. Diagrammatic Section of Fresh-water Sponge, 

9. Morphology and Reproduction of Spongida, .... 

10. Parametrium, ........ 

11. Vaginicola, Stentor, and Vorticella, ..... 

12. Diagram of Sea-anemone, ....... 

13. Morphology of Hydrozoa , ...... 

14. Tubularia indivisa, . . . 

15. Morphology of Corynida, ...... 

16. Reproductive Processes of Hydrozoa, .... 

17. Morphology of Sertularida , ...... 

18. Gonophore of one of the Campanularida, .... 

19. Dipbyes appendiculata, ....... 

20. Portuguese Man-of-War and Velella, .... 

21. Naked-eyed Medusa), ....... 

22. Lucernaria auricula, ........ 

23. Development of Lucernarida, ...... 

24. Generative Zooid of one of the Lucernarida, 

25. Transverse Sections of Adinozoa and Hydrozoa , 

26. Morphology of Actinidce, . . . \ . . 

27. Structure of Coral-reefs, ....... 

28. Pennatula phosphorea, ...... 

29. Morphology of Corals, . . . . . ... 

SO. Fleurobrachia pileus, ....... 

31. Morphology of Echinoidea, ...... 

32. Cidarispapillata, ....... 


16 

28 

30 

34 

33 

39 

40 

41 

42 
46 
48 
51 
53 
61 
62 
63 

67 

68 
71 
73 
75 

78 

79 
81 

85 

86 
89 

91 

92 

93 

97 

98 


\ 











X 


LIST OF ILLUSTRATIONS. 


FIG. 

33. Cribella oculata , ..... 


PAGE 

. 100 

34. Morphology of Ophiuroidea, .... 

. 

102 

35. Comatula rosacea , ..... 

• 

. 103 

36. Ehizocrinus Lofoten sis, .... 


. 104 

37. Cystidean, ...... 

. 

. 105 

38. Holothurian, ...... 


106 

39. Morphology of Tceniada, 

. 

. 109 

40. Morphology of Trematoda, .... 


112 

41. Morphology of Turbellaria, 


. 113 

42. Free Nematodes, ..... 


115 

43. Morphology of JRotifera, .... 


. 116 

44. Diagram of an Annulose Animal, 


118 

45. Syrinx nudus , ..... 


. 119 

46. Section of an Annelide, .... 


120 

47. Morphology of Eirudinea, 


. 122 

48. Morphology of Tubicola , 


123 

49. Morphology of Errant Annelidcs, 


. 124 

50. Lobster, ...... 


130 

51. Spiny Spider-crah, . . « . 


. 132 

52. Morphology of Isopoda , .... 


133 

53. King-crab, ..... 


. 134 

54. Pterygotus Anglicus , ..... 


134 

55. Morphology of Trilobites, 


. 135 

56. Fresh-water Entomostraca , .... 


136 

57. Morphology of Cirripedia, 


. 137 

571. Morphology of Podosomata and Acarina , . 


141 

58. Scorpion, ...... 


. 142 

59. Theridion riparium , ..... 


143 

60. Scolopendra , ..... 


. 145 

61. Millipede, ...... 


145 

62. External Anatomy of Insect, 


. 147 

63. Digestive Apparatus of Beetle, 


148 

64. Metamorphosis of Magpie-moth, 


. 151 

65. Aphis fabce , ...... 


154 

66. Cockroach, ..... 


. 155 

67. Migratory Locust, ..... 


156 

68. Aphis-lion, ..... 


. 157 

69. Termes bellicosus , ... 


157 

70. Tipula oleracea , ..... 


. 158 

71. Larva, Pupa, and Imago of Cabbage-butterfly, 


159 

72. Gooseberry Saw-fly, .... 


. 161 

73. Myrmica rufa , ..... 


162 

74. Cockchafer, ..... 


. 163 

75. Diagram of a Mollusk, .... 


164 

76. Morphology of Polyzoa , .... 


. 169 

77. Flustra, Valkeria, and Lophopus , 

_ 

170 

78. Morphology of Tunicata, 


. 172 











LIST OF ILLUSTRATIONS. 


xi 


FIG. 

79. Lingula anatina , 

80. Anatomy of a Bivalve Mollusk, 




• 

v 

PAGE 

175 
. 177 

81. Shells of Lamellibranchiata , 

82. Ampullaria canaliculata , 




• 

• 

178 
. 181 

83. Tongue of Whelk, 

84. Shells of Gasteropoda , 






182 

. 183 

85. Doris Johnstoni , 

86. Carinaria cymbium , 






184 

. 184 

87. Limax Sowerbyi , 

88. Morphology of Pteropoda , 






185 

. 18G 

89. Sepiola Atlantica , 

90. Paper Nautilus, . 






187 
. 191 

91. Pearly Nautilus, 

92. Orthoceras , .... 






193 

. 193 

93. Diagram of Invertebrata and Vertebrata , 






196 

94. Lumbar Vertebra of Whale, and Diagram of Thoracic 

Vertebra, 

. 198 

95. Skeleton of Beaver, . . . 

96. Fore-limb of Chimpanzee, 






199 

. 200 

97. Hind-limb of Chimpanzee, . 

98. Digestive System of a Mammal, 



• 



200 

. 202 

99. Blood-corpuscles of Vertebrata , 

100. Scales of Fishes, .... 



• 



203 
. 207 

101. Skeleton of Perch, 

102. Outline of a Fish, 



• 



208 

. 209 

103. Tails of Fishes, 

104. Diagram of the Circulation of a Fish, . 






210 

. 211 

105. Diagram of the Lancelet, 

106. Lamprey, ..... 






215 
. 217 

107. Ganoid Fishes, 

108. Cephalaspis Lyellii , 






221 

. 222 

109. White Shark and CTiimaera , 

110. Lepidosiren annectens , 






222 

. 224 

111. Siphonops annulatus , 

112. Axolotl, ..... 






227 
. 228 

113. Great Water-newt, . 

114. Tree-frog, ..... 






229 

. 230 


115. Development of the Common Frog, 

116. Skull of a Python, 

117. Diagram of the Circulation of a Reptile 

118. Skeleton of a Tortoise, . 

119. Hawk’s-bill Turtle, . 

120. JVaja Haje , 

121. Eye and Head of Viper, 

122. Slow-worm, . . 

123. Sdncus officinalis, 

124. Crocodilus vulgaris , 

125. Ichthyosaurus, 


. 235 

237 
. 239 

240 
. 241 

243 
. 246 
247 
. 248 
249 










LIST OF ILLUSTRATIONS 


xii 


FIG. 







PAGE 

126. Plesiosaurus, 

• • 



• 


. 

250 

127. Pterodactyle, 

• 


. 


• 


251 

128. Shoulder-girdle and Fore-limb of Penguin, 



• 


. 

256 

129, Hind-limb of the Loon, 

• 




• 


257 

130. Digestive System of the Fowl, . 






. 

259 

131. Penguin, .... 

• 

• 





266 

132. Common Heron, . . . 






. 

268 

133. Apteryx Australis, 

• 

• 





270 

134, Rock-pigeon, 

• • 





. 

272 

135. Purple-capped Lory, 

• 

• 





274 

136. Heads and Feet of Insessores, 






. 

275 

137. Foot of Peregrine Falcon and Head of Buzzard, 






277 

138. Foot and Head of Owl, . 



• 



. 

278 

139. Archaeopteryx macrura, 

• 




• 


279 

140. Lower Jaw of Chimpanzee, 

• • 


• 



. 

283 

141. Diagram of the Circulation in a Mammal, . 

• 



« 


285 

142. Ornithorhynchus , . 



• 



. 

289 

143. Phascolarctos cinereus, . • 

, 




• 


290 

144. Chlamyphorus truncatus, 



• 



. 

292 

145. Dugong, .... 

. 






294 

146. Delphinus delphis, 



• 



. 

296 

147. Feet of Ungulata, 

. 






297 

148. Head of Two-horned Rhinoceros, 



• 



. 

298 

149. Stomach of Sheep, 

. 






300 

150. Head of Cervus elaphus , . 



• 



. 

302 

151. Head of Strepsiceros Koodoo, 

. 

• 





303 

152. Skull of Indian Elephant, 

• • 





• 

305 

153. Feet of Carnivora, 

# 

• 





306 

154, Greenland Seal, . 

• • 


• 

m 


m 

307 

155. Skull of Beaver, 


• 



• 


310 

156. Hamster, .... 

•. • 


• 

0 



310 

157. Skeleton of a Bat, 


• 

• 


• 


312 

158. European Mole, . 



• 

. 



314 

159. Cercocebus sabceus, . . 


• 



• 


317 

160. Skulls of Orang and European Adult, 

• • 


• 

• 


• 

318 









ZOOLOGY. 


INTRODUCTION. 

1. Definition of Biology and Zoology. 

All natural objects may be roughly divided into three 
groups constituting the so-called Mineral, Animal, and Vegeta¬ 
ble kingdoms. The objects comprised in the mineral kingdom 
are all devoid of life, and they exhibit the following characters: 
a. Their chemical composition is simple. They consist of 
either a single element, as is the case, for instance, with native 
gold; or, if combined, they are almost always in nature in the 
form of simple compounds, composed of no more than two or 
three elements—as, for example, common salt, limestone, plas¬ 
ter of Paris, and many others, b. Mineral bodies are, when 
unmixed, composed of similar particles, which have no definite 
relations to one another, or, in other words, they are homo¬ 
geneous. c. The form of mineral bodies is either altogether 
indefinite, when they are said to be “ amorphous; ” or, if they 
have a definite shape, they are crystalline, in which case they 
are usually bounded by plane surfaces and straight lines, d. 
When mineral bodies increase in size, as crystals may do, the 
increase is produced simply by the addition of particles from 
the outside (technically called “ accretion ”). e. Mineral bodies 
exhibit no phenomena which are not purely physical and chem¬ 
ical, and they show no tendency to periodic changes of any 
kind. 

All the bodies which exhibit these characteristics properly 
belong to the mineral kingdom, and fall to be treated of by the 
sciences of Geology, Mineralogy, Chemistry, and Physics. It 



2 


INTRODUCTION. 


should be borne in mind, however, that, in the case of what are 
called “ fossils ” or “ petrifactions,” we have mineral bodies 
which owe their existence and characters to living beings 
which existed at former periods in the history of the earth. 
For this reason, fossils, though composed of mineral matter, 
can hardly be said properly to belong to the mineral kingdom. 

On the other hand, the objects which belong to the animal 
and vegetable kingdoms differ from those which are comprised 
in the mineral kingdom in the following points: a. They are 
composed of few chemical elements, of which carbon, hydro¬ 
gen, oxygen, and nitrogen, are the most important; and these 
elements are combined to form complex organic compounds, 
which always contain a large proportion of water, are very un¬ 
stable, and are prone to spontaneous decomposition, b. They 
are compo’sed of diverse or heterogeneous parts, which have 
usually more or less definite relations to one another. These 
heterogeneous but related parts are termed “ organs,” and the 
objects possessing them are said to be “ organized.” Some of 
the lowest forms of animals have bodies composed of so uni¬ 
form a substance that they cannot be said to be organized, as 
they exhibit no definite organs. This exception, however, does 
not affect the general Value of this distinction, c. They are 
always more or less definite in shape, presenting concave and 
convex surfaces, and being bounded by curved lines, d. When 
they increase in size, or “ grow,” they do so, not by the addi¬ 
tion of particles from the outside, but by the reception of 
foreign matter into their interior and its assimilation there 
(technically called “intussusception”), e. They invariably 
pass through certain periodic changes in a definite and dis¬ 
coverable order; these changes constituting life. They are 
subject to the same physical and chemical laws as those which 
govern dead matter, but the living body is the seat of some¬ 
thing in virtue of which it can override the physical laws which 
enslave mere dead matter. The living body, so long as it is 
a living body, is the seat of energy , and can overcome the 
primary law of the inertia of matter. It has certain relations 
with the outer world other than the merely passive ones of 
dead matter. However humble it may be, and even if it be 
permanently rooted to one place, some part or other of every 
living body possesses the power of spontaneous and inde¬ 
pendent motion—a power possessed by nothing that is dead. 
In the higher animals the relations of the living body to dead 
nature become still further complicated, and their mastery 
over the physical forces becomes more and more pronounced, 


INTRODUCTION 


3 


till in man, whose complex organization is wielded by an un¬ 
dying intelligence, we have a being in whose hands the dead 
matter of the universe is obedient as plastic wax. f If our 
observation be continued for a sufficient length of time, we 
always discover that every living body has the power, by more 
or less complex process, of reproducing its like. That is to 
say, it has the power, directly or indirectly, of giving origin 
to minute germs, -which can be developed under proper con¬ 
ditions into the likeness of the parent, g. Lastly, all living 
beings alike appear to be primitively composed of a substance 
which is more or less closely allied to albumen or white-of-egg, 
and which has been termed “protoplasm.” Vital phenomena 
can apparently be manifested by no other form of matter, and 
protoplasm bears to life the same relation that a conductor 
does to the electric current. It is the necessary vehicle and 
medium through which life is brought into relation w T ith the 
outer world. It does not, however, follow from this, as has 
been assumed, that protoplasmic matter holds any other or 
higher relation to life, or that vital phenomena are in any 
way an inherent property of the matter by which they are 
manifested. 

All the objects, then, which fulfil these conditions, are said 
to be alive; and they all belong either to the animal* or to the 
vegetable kingdom.* The study of living objects of all kinds, 
irrespective of which kingdom they belong to, is conveniently 
called by the general name of Biology (Gr. bios , life; and 
logos , discourse). As all living objects, however, may be re¬ 
ferred to one or other of these two kingdoms, so Biology may 
be divided into the two sciences of Botany , which treats of 
plants, and Zoology (Gr. zoon , animal; logos , discourse), which 
treats of animals. The term Natural History, again, is gen¬ 
erally understood nowadays as being equivalent to Zoology 
alone, though originally it was applied to the study of all 
natural objects indiscriminately. 


2. Differences between Animals and Plants. 


It now becomes necessary to inquire into the differences 
-which subsist between animals and plants, and which enable 
us to separate the kindred sciences of Zoology and Botany. It 
might have been thought that nothing could be easier than to 


* As will be mentioned immediately, it has been proposed to form an intermediate king¬ 
dom between the animal and vegetable kingdoms for the reception of organisms which 
cannot certainly be stated to be either plants or animals. There does not appear, however, 
to be any necessity for this in the mean while. 


4 


INTRODUCTION. 


determine the animal or vegetable nature of any given or¬ 
ganism ; and such, indeed, was the almost universal belief 
of older observers. In point of fact, however, no hard-and-fast 
line can be drawn, in the present state of our knowledge, be¬ 
tween the animal and vegetable kingdoms, and it is often a 
matter of extreme difficulty, or even wholly impossible, to 
decide positively whether we are dealing with an animal or a 
plant. So deeply has this difficulty been felt of late, that a 
most able zoologist—Dr. Ernst Haeckel—has proposed to 
form an intermediate kingdom, wffiich he calls the Regnum 
Prolisticum , and in which he proposes to place all organisms 
of a doubtful character. Even such a cautious observer as 
Professor Rolleston, while questioning the propriety of this 
step, is forced to come to the conclusion that “ there are or¬ 
ganisms which at one period of their life exhibit an aggregate 
of phenomena such as to justify us in speaking of them as ani¬ 
mals, while at another they appear to be as distinctly vege¬ 
table.” In the case of the higher members of the two king¬ 
doms there is no difficulty in arriving at a decision. The 
higher animals are readily separated from the higher plants 
by the possession of a distinct nervous system, of locomotive 
power which can be voluntarily exercised, and of an internal 
cavity fitted for the reception and digestion of solid food. The 
higher plants, on the other hand, possess no nervous system or 
organs of sense, are incapable of voluntary changes of place, 
and are not provided with any definite internal cavity, their 
food being wholly fluid or gaseous. 

The lower annuals (Protozoa) cannot, however, be separated in many 
cases from the lower plants ( Protophyta ) by these distinctions, since many 
of the former have no digestive cavity, and are destitute of a nervous system, 
and many of the latter possess the power of active locomotion. In determin¬ 
ing, therefore, the nature of these ambiguous organisms, the following are 
the chief points to be attended to: 

Firstly , as to mere form or external configuration, no certain rules can 
be laid down for separating animals and plants. Many of the lower plants, 
either in their earlier stages of existence or when grown up, are exactly 
similar in form to some of the lower animals. This is the case, for ex¬ 
ample, in some of the Alga, which closely resemble some of the Infusorian 
animalcules. Many undoubted animals, again, are rooted to solid objects 
in their adult state, and are so plant-like in appearance as to be always 
popularly regarded as vegetables. This is the case with manv of the 
so-called hydroid zoophytes, such as the sea-firs, and also with the much 
more highly organized sea-mats ( F/ustra ), all of which are usually regarded 
as sea-weeds by seaside visitors. This is also, but less strikingly, the case 
with the corals and sea-anemones, of which the latter are often spoken of as 
“ sea-flowers.” 

Secondly , no decided distinction can be drawn between animals and 


INTRODUCTION. 


5 


plants as to their minute internal structure. Both alike consist essen¬ 
tially of minute solid particles (molecules or granules), of cells, or of 
fibres. 

Thirdly, as regards chemical composition , there are some decided, though 
not universal, differences between plants and animals. As a general rule, it 
may be stated that plants exhibit a decided predominance of what are 
known to chemists as “ ternary compounds ”—that is to say, compounds 
which, like sugar, starch, and cellulose, are composed of the three elements, 
carbon, hydrogen, and oxygen. They are, comparatively speaking, poorly 
supplied with “ quaternary ” compounds, which contain the fourth element, 
nitrogen, in addition to the three first mentioned (e. g., gluten and legumin), 
Animals, on the other hand, are rich in quaternary nitrogenized compounds, 
such as albumen or fibrine. Still in both kingdoms we find nitrogenized 
and non-nitrogenized compounds, and it is only in the proportion which 
these bear to one another in the organism that animals differ in any way 
from plants. The most characteristic of all vegetable compounds is the one 
known as cellulose , very nearly allied in its chemical composition to ordinary 
starch. As a general rule it may be stated that the presence of an external 
envelope of cellulose in any organism raises a strong presumption as to its 
vegetable nature. Still cellulose is not exclusively confined tQ plants, as 
was at one time believed. It is now well known that the outer covering 
of the so-called sea-squirts or Ascidian Mollusks contains a large quantity 
of cellulose (as much as 60 per cent, in some cases); and recent researches 
seem to prove that this substance is present also in some of the lower forms 
of animal life (coccospheres). Another highly characteristic vegetable prod¬ 
uct is chlorophyll , the green coloring-matter of plants. Any organism 
which exhibits chlorophyll in any quantity as a proper element of its tissues 
is most probably vegetable. In this case also, however, the presence of 
chlorophyll cannot be regarded as a certain test, since it occurs regularly in 
some undoubted animals (e. g., Stentor among the Infusoria , and the Hydra 
viridis, or green fresh-water polype, among the Gcelenterata). 

Fourthly , as regards locomotive power, or the ability to effect changes of 
place at will, the results of observation are singularly at variance with our 
preconceived notions. Before the invention of the microscope, no instances 
of independent voluntary movements were known in plants, if we except the 
voluntary opening and closure of flowers and their turning toward the sun, 
the drooping of the leaves of sensitive plants under irritation, and some 
other phenomena of a like nature. Now, however, we know of many plants 
which are endowed, either when young or throughout life, with the power 
of effecting voluntary movements apparently as spontaneous and independent 
as those exhibited by the lower animals. In some cases the movements are 
brought about by means of little vibrating hairs or cilia with which a part 
or the whole of the surface is furnished. In other cases the movements 
seem to be certainly not produced by cilia, but their exact cause is obscure 
(e. g., in the Diatomacece and Desmidice , two of the lower orders of plants, all 
of which are microscopic in size). When it is added that many animals are 
permanently fixed and rooted to solid objects in their fully-grown condition, 
it will be seen that no absolute distinction can be drawn between animals 
and plants merely on the ground of the presence or absence of independent 
locomotive power. 

Fifthly , we have shortly to consider one of the most reliable of all the 
tests by which an animal may be separated from a plant—namely, the nature 
of the food, and the products which are formed out of the food within the 
body. 


6 


INTRODUCTION. 


The differences between animals and plants in this respect may be roughly 
stated as follows: 

1. Plants live upon purely dead or inorganic substances, such as water, 
carbonic acid, and ammonia—and they have the power of making out of 
these true organic substances, such as starch, cellulose, sugar, etc. Plants, 
therefore, take as food very simple bodies, and manufacture them into 
much more complex substances, so that plants are the great producers in 
nature. 

2. Plants in the process of digestion break up carbonic acid into the two 
elements of which it is composed—namely, carbon and oxygen, keeping the 
carbon and setting free the oxygen. As carbonic acid occurs always in the 
air in small quantities, the result of this is that plants remove carbonic acid 
from the atmosphere and give out oxygen. 

3. Animals, on the other hand, have no power of living on dead or in¬ 
organic matters, such as water, carbonic acid, and ammonia. They have no 
power of converting these into the complex organic substances of which 
their bodies are composed. On the contrary, animals require to be supplied 
with ready-made organic compounds if their existence is to be maintained. 
These they can only get in the first place from plants, and therefore ani¬ 
mals are all dependent upon plants for food either directly or indirectly. 
Animals, therefore, differ from plants in requiring as food complex organic 
bodies which they ultimately reduce to very much simpler inorganic bodies. 
While plants, then, are the great manufacturers in nature, animals are the 
great consumers. Another distinction arising from the nature of their food 
is, that while plants decompose carbonic acid, keeping the carbon and setting 
free the oxygen, animals absorb oxygen and give out carbonic acid, so that 
their reaction upon the atmosphere is the reverse of that of plants. 

As regards these general distinctions between plants and animals, there 
are three points which should be remembered: 

1. That, even if universally true, these distinctions can often not be ap¬ 
plied in practice to the ambiguous microscopic organisms about which alone 
any doubt can be entertained. 

2. These general laws are certainly not of universal application in the 
case of plants. Some fungi are known which in the matter of food are ani¬ 
mals—that is to say, they cannot live upon inorganic materials alone, but 
require ready-made organic products for their support. 

3. Recent researches have rendered it not unlikely that some of the 
lower animals have the power of acting as plants, and of manufacturing 
organic compounds out of inorganic materials. 

3. Classification. 

By the term classification is understood the arrangement 
of a number of dissimilar objects of any kind into larger or 
smaller groups according as they exhibit more or less likeness 
to one another. The number of different animals is so enor¬ 
mous that it was long ago perceived that some classification 
of them, or method of arranging them into groups, was abso¬ 
lutely indispensable. Without some such arrangement it would 
have been utterly impossible to have ever acquired a clear 
notion of the animal kingdom as a whole. In the older 


INTRODUCTION. 


1 


arrangements, animals were grouped in accordance with some 
particular character, which might or might not be a really 
essential one; and the result was that these classifications 
were “artificial,” and not “natural,” as they are when all the 
characters are taken into consideration. To take a familiar 
example of this: when we speak of “ quadrupeds,” we really 
do so in consequence of our having, consciously or uncon¬ 
sciously, formed something like a rough classification of the 
animal kingdom. We have a dim idea that all animals with 
four legs belong together somehow, and form a single group. 
Our classification, however, is founded upon a single character 
only—the possession, namely, of four legs; and it is, there¬ 
fore, a purely artificial arrangement. It will, however, be 
practically good or bad, just as this single character expresses 
a genuine and fundamental distinction, or is of a merely trivial 
and superficial nature. The instance here chosen will serve to 
illustrate either case. If we insist upon the fact that all the 
four legs must be externally visible, unmistakable legs, never 
fewer in number than four, then our classification is a*very bad 
one, in fact entirely “ artificial.” In this case our group of 
“ quadrupeds ” will comprise only the ordinary four-legged 
mammals, such as oxen, sheep, horses, and such-like—together 
with the very dissimilar groups of the four-legged reptiles and 
amphibians, such as tortoises, lizards, crocodiles, frogs, and 
newts. Now, these different animals have certainly much in 
common, but we are not justified in placing them together 
simply upon the ground that they have four conspicuous legs, 
unless we are willing to put in a vast number of other animals 
as well. We must, in fact, put in a great number of animals 
which are not quadrupeds in the sense that they have four legs, 
but which agree with those that have four legs in the other 
fundamental and essential points of their structure. In this 
way we may arrive at a very genuine and natural classification 
by making some concessions. We must allow, for instance, 
that two of the legs or limbs, ceasing to be fit for walking, 
may be converted into organs of flight, or wings. This will 
let in the birds. We must allow, again, that all the limbs 
may be converted into Jins. This admits most of the fishes. 
We must further grant that two of the legs may be altogether 
absent while the remaining two are converted into swimming- 
paddles. This will bring in the whales and dolphins. Lastly 
—and this is the greatest admission of all—we must allow 
the total absence of all the limbs, provided the animal only 
show those other essential characters which are invariably 


8 


INTRODUCTION. 


found to go along with the possession of four legs in the regu¬ 
lar quadrupeds. This will bring in the snakes and some of 
the fishes. So that, paradoxical as it may seem, it is in one 
sense scientifically correct to speak of a snake as a quadruped, 
though in reality it has no legs at all. In other words, there 
is no reason why a snake should not some day be found with 
four legs, and in point of fact some snakes show rudiments of 
these appendages. Making these allowances, and some more 
of a similar nature, we may ultimately succeed in converting 
our division of Quadrupeds into a strictly scientific group, 
comprising the Mammals, the Birds, the Reptiles, the Amphi¬ 
bia, and the Fishes. In fact, our group of Quadrupeds now 
agrees exactly with the great and natural division of the Ver- 
tebrata or vertebrate animals. It is true that all vertebrate 
animals have not got four limbs, or not obviously so, but they 
never have more than four under any circumstances; and a 
closer examination soon show r s us that they agree with one 
another in many other characters which are of much greater 
importance than the characters of the limbs alone. 

We have arrived, then, at the grand principle of all good 
classification—namely, that we should group together those 
objects only which are united by essential and fundamental 
points of similarity, and that in so doing w r e should ignore all 
mere superficial resemblances. The question now arises, 
What are these essential and fundamental points in the case 
of animals ? 

If for the moment we look at animals simply as so many 
machines, we shall not find much difficulty in answering this 
question. Let us suppose ourselves placed in a gigantic 
w orkshop full of an immense number of complicated and curi¬ 
ously-constructed machines of different sorts, and asked to put 
them in order—to put those of one kind in one place, and 
those of another kind in a different place. How should we 
proceed to act ? Supposing, in the first place, that all the 
machines were at a stand-still, all that could be done w T ould 
be to examine carefully the external form and internal struct¬ 
ure of each, and to do our best to pick out some peculiarity 
which w r oukl distinguish some from all the others. In this 
way, if our mechanical knowledge were sufficiently extensive, 
we should no doubt ultimately succeed in classing all our ma¬ 
chines into something like a rough natural arrangement. We 
should, for instance, have those made on the principle of the 
lever in one place, those on the principle of the inclined plane 
in another, and those on the principle of the pulley in a third. 


INTRODUCTION. 


9 


Still our classification would most certainly be imperfect, and 
in some cases altogether incorrect. In some instances the 
parts of the machine would be so complex as to be utterly in¬ 
comprehensible, and in many cases our ignorance of what 
each was intended to effect would be an insuperable bar to 
our arriving at any arrangement. Suppose now, however, 
that all the machines were suddenly set in motion, so that we 
could see not only the manner in which they were constructed 
and the materials of which they were composed, but could 
also see what they could do —could see, in fact, for what work 
each is intended. The task of arrangement now becomes im¬ 
mensely easier. Our previous classification, founded simply 
upon the structure of the machines, is now supplemented and 
rectified by our knowledge of what each is able to effect. 
One machine is found performing one set of actions, another a 
different set; and in this way not only is our classification 
rendered much easier, but we now get an insight into the 
meaning and nature of many points of structure which were 
formerly obscure. 

To make this illustration fully meet the case of the natu¬ 
ralist who deals with living beings only, we have simply to 
suppose that the machines to be examined are reasonably per¬ 
fect in their parts and fit for work, and that our imaginary 
workshop is supplied w T ith a reasonable amount of light, not 
very brilliant, perhaps, and striking upon some objects more 
sharply than on others, but still upon the whole moderately 
steady and uniform. Far worse, however, is the case of the 
naturalist who has to deal with the remains of extinct gen¬ 
erations of animals and plants, whose work lies among those 
relics of a by-gone world which are known as “ fossils ” or 
“ petrifactions ”—objects in many cases more wonderful and 
more perplexing and more beautiful than the most ornate and 
elaborate productions of human skill. In his case the work¬ 
shop is a vast and gloomy vault or charnel-house, with no in¬ 
ternal source of light, and but fitfully illuminated by uncer¬ 
tain gleams from the world without. And what is worse than 
this, his machines are mutilated and defaced, in many cases 
wanting their most important parts, in all cases destitute of 
life and motion, and usually very unlike any thing visible at 
the present da}\ Nevertheless it is almost incredible with 
what certainty and precision a mere fragment of a fossil, a 
single tooth or bone, can be referred by a skilled worker in 
this field of science to its proper place in the animal kingdom 
—with v T hat exactitude the missing parts can be restored— 


10 


INTRODUCTION. 


and what splendid generalizations can be drawn from what at 
first sight would appear to be the most fragmentary evidence. 

This imaginary illustration exactly expresses the points 
which are to be regarded as essential and fundamental in clas¬ 
sifying and arranging animals. We have to look, namely, 
firstly , to the plan upon which each animal is constructed; 
secondly , to the manner in which it discharges its vital func¬ 
tions. These are the two points of view from which every 
organism may be regarded—in their nature quite distinct, and 
indeed sometimes apparently opposite. From the one point 
of view we have to look solely to the laws, form, and arrange¬ 
ment of the structures of the organism. This constitutes what 
is technically called u Morphology,” or the science of form 
(from the Greek words, morphe , form ; and logos, a discourse). 
From the second point of view, we are concerned simply with 
the functions discharged by the different parts of the organ¬ 
ism, and this constitutes what is known as “ Physiology.” It 
is most important to remember that there are no other points 
in which it is possible for one animal to differ from another. 
If two animals are different, they must differ in one or other 
or in both of these points. Either they differ morphologically , 
in being constructed upon altogether different plans; or they 
differ physiologically , in performing a different amount of 
vital work in a different manner, and with different instru¬ 
ments ; or they differ both morphologically and physiologi¬ 
cally. Philosophical classification, therefore, insomuch as it 
depends entirely upon a due appreciation of what are the 
real differences between different animals, is nothing more 
than an attempt to express formally the facts and laws of Mor¬ 
phology and Physiology. 

Examining next into the nature and extent of the morpho¬ 
logical or structural differences between different animals, we 
find that these are much less and much fewer than might have 
been thought. By one not previously acquainted with the 
subject, it might readily be supposed that every kind of ani¬ 
mal was constructed upon a type or plan peculiar to itself and 
not shared by any other. We should certainly suppose, for 
example, that animals so different as a lobster and a butterfly 
were built upon different types or plans of structure. When 
we come, however, to examine the question, we find that this 
is not the case. The lobster and the butterfly are constructed 
upon the same structural plan or morphological type. What 
is still more remarkable, we find that all known animals, in 
spite of their immense differences in external appearance, are 


INTRODUCTION. 


11 


really constructed upon no more than some half-dozen primary 
plans of structure or morphological types. These types are 
all different from one another, but there is no animal yet 
known to us, living or extinct, which cannot be referred to 
one or other of these six plans. These plans, then, give us the 
primary basis for a classification of the animal kingdom—all 
the animals formed upon one plan being grouped together so 
as to form a single division. The animal kingdom, therefore, 
is primarily divided into six great sections corresponding to 
the six morphological types, and these sections are known to 
naturalists under the name of the “ sub-kingdoms.” Each of 
these sub-kingdoms has its special name, and it is the object 
of the present work to describe the leading characters and 
more important examples of each. 

We have to understand, then, that all the animals belong¬ 
ing to each sub-kingdom agree with one another in their mor¬ 
phological type, or, in other words, in the plan upon which 
they are constructed ; and the question now arises how they 
can be separated from each other. If they agree morphologi¬ 
cally, there is only one other way in which they can differ, 
and that is physiologically , in the manner in which they dis¬ 
charge their vital functions. Consequently, all animals which 
agree with one another in their plan of structure, and which 
are therefore placed in the same sub-kingdom, are separated 
from one another solely by their physiological perfection. In 
other w r ords, as machines, they are constructed of the same 
fundamental parts, but they do their work in a different way 
and with different instruments. 

Returning to our old illustration, suppose we had sepa¬ 
rated from the mass of machines before us all those which 
were intended to mark the lapse of time, and had in this way 
assembled a large collection of hour-glasses, watches, time¬ 
pieces, and clocks, and suppose that we wanted to arrange 
these more minutely, we should soon discover that each of 
these different time-keepers was formed upon a principle pe¬ 
culiar to itself. The hour-glasses, as the most simple, would 
form one division ; the timepieces and clocks, possessing pen¬ 
dulums, would form another; and the watches would form a 
third. These, as being constructed upon different plans, would 
constitute three distinct groups, which we should call classes 
or sub-kingdoms according to the value we might see fit to 
place upon the differences between them. But we must fur¬ 
ther suppose that we wished to divide one of these groups— 
say the watches—into still smaller groups. If they w T ere all 


12 


INTRODUCTION. 


standing, we should probably find this a matter of very great 
difficulty. The moment, however, that they commenced to 
go—or, in other words, to perform their own peculiar func¬ 
tion—we should soon see that some would be different to 
the others. Some, for instance, would strike the hours, and 
these would have to be laid aside in a group by themselves. 
And we should further discover that, in accordance with the 
difference in the function , there would be an equivalent dif¬ 
ference in the structure , of these two groups. The striking 
watches would be formed upon the same fundamental type as 
those which did not strike ; but, in addition to the broad and 
general details of structure in which all were the same, the 
striking watches would have a special apparatus or structure 
fitted for striking the hours. The non-striking watches would 
be destitute of this apparatus, so that the physiological or 
functional difference between the two groups would thus en¬ 
tail a corresponding difference in structure. 

It is just the same with animals. If we take a lobster, a 
butterfly, a scorpion, and a spider, we find that, dissimilar as 
they are in external appearance, they are all constructed upon 
the same fundamental plan. They agree in morphological 
type, and they belong to the same sub-kingdom. They lead 
different lives, however—they are placed under different con¬ 
ditions—and they discharge different functions in the general 
economy of Nature. They differ, therefore, physiologically ; 
and, as every physiological difference implies a corresponding 
structural difference, they differ structurally as well. But 
they differ structurally only because they differ physiologi¬ 
cally, and in all the really essential details of their structure 
they are the same. The lobster is aquatic in its habits, and 
has therefore gills, or organs adapted for breathing air dis¬ 
solved in water. The butterfly is aerial, and has respiratory 
organs adapted for breathing air directly, and not through the 
medium of water. They differ, then, physiologically, and 
therefore, necessarily, in the corresponding structure. Both, 
however, have distinct organs set apart and dedicated to the 
function of respiration. This is an essential and fundamental 
point in their structure, and in this they both agree with one 
another, and differ from a large number of animals in which 
there are no distinct breathing-organs. It is only by the com¬ 
bined effect of a number of these physiological differences, 
taken collectively, that the lobster and the butterfly come ulti¬ 
mately to be so strikingly distinct from one another 

It is now possible to comprehend fully the principles upon 


INTRODUCTION. 


13 


which a naturalist proceeds in framing a classification of the 
animal kingdom. Ilis great primary divisions are founded up¬ 
on differences in the smaller and fundamental details of struct¬ 
ure. His smaller divisions are based upon the less important 
physiological differences with their corresponding structural 
distinctions. Of course, in carrying out this programme of a 
truly philosophical and natural classification, the naturalist 
works to a great extent in the dark, and is liable to many 
sources of error. It is by no means always easy to deter¬ 
mine what points of structure are essential and fundamental, 
and what are only caused by physiological differences. Such, 
too, is the constitution of the human mind, that different ob¬ 
servers place different values upon the same structures; points 
which some look upon as of essential value are regarded by 
others as of a merely superficial nature. Nevertheless there 
can be no doubt that the progress of Natural History as a 
science has been strictly conterminous with the development 
of these great principles of classification. 

In the present work an outline is given of the morpho¬ 
logical differences between all the larger groups of the animal 
kingdom, but it may be as well here to say a few words upon 
the subject of Physiology. As already remarked, Physiology 
treats of all the functions exercised by living bodies, or dis¬ 
charged by the various definite parts or organs of which most 
animals are composed. All these various functions come un¬ 
der three great heads : 1 . Functions of Nutrition, comprising 
all those functions by means of which an animal is able to live, 
grow, and maintain its existence as an individual. 2. Func¬ 
tions of Reproduction , comprising all the functions by which 
fresh individuals are produced and the perpetuation of the 
species insured. 3. A series of functions which are known 
by the somewhat misleading name of the Functions of Rela¬ 
tion or of Correlation. Under this term are included all those 
functions by means of which external objects are brought into 
relation with the organism, and by which it, in turn, reacts 
upon the outer world. The functions of nutrition and repro¬ 
duction are often spoken of collectively as the functions of 
“ organic ” or u vegetative ” life, as being common to animals 
and plants alike. The functions of relation, again, are often 
called the functions of “ animal ” life, as being most highly 
developed in animals. These functions, however, though more 
highly characteristic of animals, are not peculiar to them, bu - 
are manifested to a greater or less extent by various plants. 

As regards animals, all alike, whatever their structure may 


14 


INTRODUCTION. 


be, perform the three great physiological functions—that is to 
say, they all nourish themselves, reproduce their like, directly or 
indirectly, and have certain relations with the external world. 
When we come, however, to compare animals together physio¬ 
logically, it is soon seen that the functions of relation stand in 
quite a different position to that occupied by the functions of 
nutrition and reproduction. As far as these last are con¬ 
cerned, there can be no difference in the amount or perfection 
of the function discharged by the organism. The simplest 
and most degraded of animals—say a sponge—nourishes it¬ 
self as perfectly, as far as the result to itself is concerned, as 
does the highest of animals. Nutrition can do no more than 
maintain the body of any animal in a healthy and vigorous 
condition. This is the highest possible perfection of the func¬ 
tion, and it is attained as fully and perfectly by the sponge as 
it is by man himself. The same holds good of reproduction. 
While the functions of nutrition and reproduction are thus, as 
regards their essence and results, the same in all animals, it 
must be remembered that there are enormous differences in 
the manner in which the functions are discharged. The result 
attained is in all cases the same, but it may be arrived at in 
the most different ways and with the most different apparatus. 
As regards the functions of relation, on the other hand, we 
have every possible grade of perfection exhibited as we as¬ 
cend from the lowest members of the animal kingdom to the 
highest. So numerous, in fact, are the changes in these func¬ 
tions, and so great the additions which are made in the higher 
organisms, that it may be doubted if there exists any common 
element by which a comparison can be drawn on this head be¬ 
tween the higher and lower animals. It may reasonably be 
doubted whether in this respect a horse or a dog has any 
thing in common with a sponge. 

Instead of giving here a general sketch of each of the great 
physiological functions as a whole, it may be as well to accom¬ 
pany the morphological account of each primary division of 
animals with a short account of the manner in which the vital 
functions are carried out in the same. In this way a clearer 
view will be obtained of the gradual rise in physiological per¬ 
fection in passing from the bottom to the summit of the ani¬ 
mal series. 

Homology and Analogy. —In connection with the mor¬ 
phological and physiological differences between animals, a 
short explanation may be given of the meaning of the terms 
Homology and Analogy, which are in constant use in zoologi- 


INTRODUCTION. 


15 


cal works, When organs in different animals agree with one 
another in their plan of structure , they are said to be “ homolo¬ 
gous,” no matter what may be the functions which they perform. 
For example, the arm of a man, the fore-leg of a horse, the wing 
of a bird, and the swimming-paddle of a dolphin or whale, are 
all composed essentially of the same structural elements, and 
they are therefore said to be homologous, though they are 
fitted for altogether different functions. 

On the other hand, when organs in different animals per¬ 
form the same functions , they are said to be “ analogous,” 
whatever their fundamental structure may be. Thus the 
wing of a bat, the wing of a bird, and the wing of an insect, 
all serve for flight, and they are therefore “ analogous ” Organs. 
They are all, however, constructed upon different plans, and 
they are, therefore, not “ homologous.” At the same time, 
however, it is to be remembered that there are plenty of cases 
in which organs in different animals are not only constructed 
upon the same plan, but also perform the same function, so 
that they are both homologous and analogous. 

General Divisions of the Animal Kingdom. 

As already stated, the entire animal kingdom may be di¬ 
vided into some half-dozen primary plans of structure or mor¬ 
phological types, to one or other of which every known animal 
is referable. These primary types are known to naturalists as 
the sub-kingdoms , under the following names: Protozoa , Coe- 
lenterata , Annuloida , Annulosa , Mollusca , and Yertebrata. The 
characters and minor subdivisions of these sub-kingdoms form 
the subject of the remainder of this work. In the mean while, 
it is sufficient to state that the first five of these are often 
grouped together under the collective name of the Inverte- 
brata y or “ invertebrate animals.” The Invertebrata , compris¬ 
ing the Protozoa , Coelenterata, Annuloida , Annulosa , and 
Mollusca , are collectively distinguished by the following 
points among others: The body, if divided transversely, or 
cut in two, shows only a single tube containing all the vital 
organs (Fig. 1, A). These organs, in the higher Invertebrata , 
consist of an alimentary or digestive cavity, a circulatory or 
“ haemal ” system, and a nervous or “ neural ” system. The 
side of the body on which the “ haemal ” or blood-vasculai 
system is placed is called the “ haemal aspect; ” while the side 
of the body on which the main masses of the nervous system 
are situated is called the “neural aspect.” When there is 


16 


INTRODUCTION. 


any skeleton, this is external (forming an “.exo-skeleton’’), 
and it is really nothing more than a hardening of the skin. 
The limbs, when present, are turned toward the neural aspect 
of the body. 

In the Vertebrata , on the other hand, the body, if trans¬ 
versely divided, exhibits two tubes. In one (Fig. 1, B) is placed 
the main mass of the nervous system (the brain and spinal 




Fig. 1.—Diagrams representing transverse sections of one of the higher Invertebrata, A— 
and one of the Vertebrata, B. a Wall of the body; b Alimentary canal; c Haemal or 
blood-vascular system ; n Nervous system; n' Cerebro-spinal axis, or brain and spinal 
cord of the Vertebrata, enclosed in a separate tube; ch Noto-chord or chorda dorsalis. 
(Slightly altered from Huxley.) 

cord). In the other tube are the alimentary canal, the haemal 
or blood-vascular system, and certain other portions of the 
nervous system, which are known as the “ sympathetic ” sys¬ 
tem of nerves, and which correspond to, or are homologous 
with, the entire nervous system of the Invertebrata. Further, 
in the Vertebrata there is always an internal skeleton (or 
endo-skeleton), the central stem of which is usually consti¬ 
tuted by a true backbone or “ vertebral column.” When this is 
not present, there is always a structure which will be after¬ 
ward described as the “ noto-chord ” or “chorda dorsalis.” 
Lastly, the limbs of the Vertebrata , when present, are never 
more than four in number, and they are always turned away 
from the neural aspect of the body—away, that is, from the 
side on which the main masses of the nervous system are 
placed. 

Subjoined is a short tabular view of the main existing 
divisions of the Animal Kingdom, the characters and smaller 
divisions of which will be considered hereafter at length: 


INTRODUCTION. 


17 


INVERTEBRATE ANIMALS. 


SUB-KINGDOM I.—PROTOZOA. 

Animal simple or forming colonies, usually very minute ; the body com¬ 
posed of the structureless, jelly-like, albuminous substance called “sarcode;” 
not divided into regular segments ; having no nervous system; no regular 
circulatory system; usually no mouth; no definite body-cavity, or at most 
but a short gullet. 

Class A. Gregarinid.® —Minute Protozoa which inhabit the interior of 
insects and other animals, and which have not the power of throwing out 
prolongations of their substance (pseudopodia). No mouth. 

Class B. Riiizopoda (Root-footed Protozoa).—Protozoa which are 
simple or compound, and have the power of throwing out and retracting pro¬ 
longations of the body-substance (the so-called “ pseudopodia ” ). No mouth, 
in most, if not in all. 

Order 1. Monera. — Ex. Protogenes. 

Order 2. Amcebea. — Ex. Proteus Animalcule (Amoeba). 

Order 3. Eoraminifera. — Ex. Lagena, Nodosaria, Globigerina. 

Order 4. Radiolaria. — Ex. Thalassicolla, Polycystina. 

Order 5. Spongida. — Ex. Fresh-water Sponge (Spongilla), Venus’s 
Flower-Basket (Euplectella). 

Class C. Infusoria (Infusorian Animalcules).—Protozoa with a mouth 
and short gullet; destitute of the power of emitting pseudopodia; furnished 
with vibratile cilia or contractile filaments; the body usually composed of 
three distinct layers. 

Order 1. Ciliata. — Ex. Bell-animalcule (Vorticella), Paramcecium. 

Order 2. Flagellala .— Ex. Peranema. 

Order 3. Suctoria. — Ex. Podophyra. 


SUB-KINGDOM II.— CCELENTERA TA. 

Animals whose alimentary canal communicates freely with the general 
cavity of the body ; body composed essentially of two layers or membranes, 
an outer layer or “ ectoderm,” and an inner layer or “ endoderm.” No cir¬ 
culatory system or heart, and in most no nervous system. Skin furnished 
with minute stinging organs or “ thread-cells.” Distinct reproductive organs 
in all. 

Class A. Hydrozoa. —Walls of the digestive sac not separated from 
those of the general body-cavity, the two coinciding with one another. Re¬ 
productive organs external. 

Sub-class I. Hydroida (Hydroid Zoophytes). 

Order 1. Hydroida. — Ex. Fresh-water Polype (Hydra). 

Order 2. Corynida. — Ex. Pipe-coralline (Tubularia). 

Order 3. Sertularida. — Ex. Sea-firs (Sertularia). 

Sub-class II. Siphonophora (Oceanic Hydrozoa). 

Order 4. Calycophoridce. — Ex. Diphyes. 

Order 5. Physophoridce. — Ex. Portuguese Man-of-War (Physalia). 

Sub-class III. Discophora (Jelly-fish). 

Order 6. Medusidce. — Ex. Trachynema. 

Sub-class IV. Lucernarida (Sea-blubbers). 

Order 7. Lucernariadce. — Ex. Lucernaria. 

Order 8. Pelagidce. — Ex. Pelagia. 

Order 9. Rhizostomidce. — Ex. Rhizostoma. 


18 


INTRODUCTION. 


Sub-class V. Graptolitid.® (extinct). 

Class B. Actinozoa. —Stomach opening below into the body-cavity, 
which is divided into a number of compartments by a series of vertical 
partitions or “mesenteries.” Reproductive organs internal. 

Order 1. Zoantharia .—Tentacles simply rounded, in multiples of five 
or six.— Ex. Sea-Anemones (Actinidae), Star-corals 

(Astraeidae), Brain-corals (Meandrina), Madrepores (Ma- 
dreporidae). 

Alcyonaria .—Tentacles fringed, in multiples of four.— Ex. 
Dead-man’s-toes (Alcyouium), Organ-pipe Coral (Tubi- 
pora), Sea-rods (Virgularia), Sea-pens (Pennatula), Red 
Coral (Corallium). 

Rugosa (extinct). 

Clenophora .—Animal oceanic, swimming b) r means of 
bands of cilia or “ ctenophores.”— Ex. Pleurobrachia, 
Venus’s Girdle (Cestum). 


Order 2. 


Order 3. 
Order 4. 


SUB-KINGDOM III.—ANNULOIDA. 

Animals in which the alimentary canal is completely shut off from the 
general cavity of the body, and in which there is a distinct nervous system. 
A true blood-circulatory system may or may not be present. In all there is 
a peculiar system of canals, which usually communicate w ith the exterior, 
and which constitute w r hat is called the “ water-vascular system.” The body 
of the adult is never composed of a succession of definite rings, or provided 
w r ith successive pairs of appendages disposed symmetrically on the two sides 
of the body. 

The Annuloida are divided into two great classes: 

A. Echinodermata. —Integument composed of numerous calcareous plates 
jointed together, or leathery and having grains, spines, or tubercles of cal¬ 
careous matter developed in it. Water-vascular system (ambulacral system) 
mostly employed in locomotion, and generally communicating with the ex¬ 
terior. Adult generally more or less starlike or “ radiate ” in shape; young 
mostly showing more or less complete “ bilateral symmetry,” that is, show¬ 
ing similar parts on the two sides of the body. Nervous system radiate. 

Order 1. Crinoidea. — (Sea-lilies). — Ex. Feather-star (Comatula). 

Medusa-head Crinoid (Pentacrinus), Stone-lily (Encri- 
nus.) 

Order 2. Blastoidea (extinct). 

Order 3. Cysioidea (extinct). 

Order 4. Ophiuroidea (Brittle-stars).— Ex. Sand-stars (Ophiura), 

Brittle-stars (Ophiocoma). 

Order 5. Asteroidea (Star-fishes).— Ex. Cross-fish (Uraster), Sun- 
star (Solaster), Cushion-star (Goniaster). 

Order 6. Ecliinoidea (Sea-urchins).— Ex. Sea-eggs (Echinus), Hcart- 
urchins (Spatangus). 

Order 7. Holothuroidea (Sea-cucumbers). — Ex. Trepangs (Holo- 
thuria). 

B. Scolecida. —Body usually flattened, or cylindrical and worm-like ; in¬ 
tegument soft, without lime. Water vascular system not assisting in loco¬ 
motion. Nervous system consisting of one or two ganglia or little masses, 
and not disposed in a radiate manner. 

Order 1. Tceniada. — Ex. Tape-worm (Taenia). 

Order 2. Trematoda (Suctorial w r orms).— Ex. Liver-fluke (Distoma). 


INTRODUCTION. 


19 


Order 3. TurbeUaria. — Ex. Flanarians (Planaria), Ribbon-worms 

(Nemertes). 

Order 4. Acanthocephala (Thorn-beaded worms).— Ex. Echino- 

rhynehus. 

Order 5. Gordiacea (Hair-worms).— Ex. Gordius. 

Order 6. Nematoda (Thread-worms).— Ex. Round-worm (Ascaris), 
Guinea-worm (Filaria), Vinegar-eel (Anguillula). 

Order 7. Jiotifcra (Wheel-animalcules).— Ex. Builder-animalcule 

(Melicerta), Flexible Creeper (Notommata). 

SUB-KINGDOM IV. — AKNULOSA. 

Animal composed of numerous definite segments or “ somites,” arranged 
longitudinally, one behind the other. Nervous system always present, con¬ 
sisting of a double chain of nervous masses, or ganglia, which are placed along 
the lower surface of the body, and form a collar around the gullet. Limbs 
(when present) turned toward that side of the body on which the main 
masses of the nervous system are situated. 

Division A. Anartiiropoda. —Locomotive appendages, when present, 
not distinctly jointed or articulated to the body. 

Class I. Gephyrea. — Ex. Spoon-worms (Sipunculus). 

Class II. Annelida (Ringed-worms). 

Order 1. Hirudinea. — Ex. Leeches (Sanguisuga, Hirudo). 

Order 2. Oligochcela. — Ex. Earth-worms (Lumbricus), Water-worms 
(Nais). 

Order 3. Tubicola. — Ex. Tube-worms (Serpula). 

Order 4. Erraniia. — Ex. Sand-worms and Sea-centipedes (Nereis), 
Lob-worm (Arenicola), Sea-mouse (Aphrodite). 

Class III. Chastognatha (Arrow-worms).— Ex. Sagitta. 

Division B. Artiiropoda. —Locomotive appendages jointed, or articu¬ 
lated to the body. 

Class I. Crustacea. —Respiration aquatic, mostly by gills. Two pairs 
of antennae. Limbs more than four pairs in number, carried upon the tho¬ 
rax, and generally the abdomen also. 


Order 

Order 

Order 

Order 

Order 

Order 

Order 

Order 

Order 

Order 

Order 

Order 

Order 

Order 


Class II. 


Water-fleas (Cypris). 

Cyclops. 

Branched-homed Water-fleas 
Brine-shrimp (Artemia). 


(Daph- 


1. Rhizocephala. — Ex. Peltogaster. 

2. Ichthyophthira. — Ex. Lernaea. 

3. Cirripedia. — Ex. Barnacles (Lepas), Acorn-shells (Bala- 

nus). 

4. Ostracoda. — Ex. 

5. Copepoda. — Ex. 

6. Cladocera. — Ex. 

nia). 

7. Phyllopoda. — Ex. 
r 8. Trilobita (extinct). 

9. Mcrosiomata. — Ex. King-crabs (Limulus). 

10. Lcemodipoda. — Ex. Whale-louse (Cyamus). 

11. I&opoda. — Ex. Wood-lice (Oniscus), Slaters (Ligia). 

12. Amphipoda. — Ex. Sandhopper (Talitrus), Fresh-water 

Shrimp (Gammarus). 

13. Stomapoda. — Ex. Locust-shrimp (Squilla). 

14. Decapoda. — Ex. Lobster (Homarus), Cray-fish (Astacus), 

Shrimps (Crangon); Hermit-crabs (Pagurus); Crabs 
(Cancer, Carcinus), Land-crabs (Gecarcinus). 
Araciinida. —Respiration aerial, by pulmonary chambers or 


20 


INTRODUCTION. 


air-tubes (tracheae) in the higher forms. Antennae converted into jaws. 
Head and thorax amalgamated. Four pairs of legs. Abdomen without 
limbs. 

Order 1. Podosomata (Sea-spiders).— Ex. Pycnogonum. 

Order 2. Monomerosomata. — Ex. Mites (Acarus), Water-mites (Hy- 
drachna), Ticks (Ixodes). 

Order 3. Adelarthrosomata. — Ex. Harvest-spiders (Phalangidae), 

Book-scorpions (Chelifer). 

Order 4. Pedipalpi. — Ex. Scorpions (Scorpio). 

Order 6. Araneida. — Ex. House-spiders (Tegenaria), Field-spiders 
(Epeira). 

Class III. Myriapoda. —Respiration aerial, by tracheae (air-tubes) or by 
the skin. Head distinct; remainder of body composed of nearly similar 
segments; legs more than eight pairs in number, and borne partly upon the 
abdomen. One pair of antennae: 

Order 1. Chilopoda. — Ex. Centipedes (Scolopendra). 

Order 2. Chilognatha. — Ex. Millipedes (lulus). 

Order 3. Pauropoda. — Ex. Pauropus. 

Class IV. Insecta. —Respiration aerial, by tracheae. Head, thorax, and 
abdomen distinct. One pair of antennae. Three pairs of legs, and gen¬ 
erally two pairs Of wings on the thorax. No locomotive limbs on the 
abdomen. 

Order 1. Anoplura. — Ex. Lice (Pediculus). 

Order 2. Mallophaga (Bird-lice). 

Order 3./ Thymnura (Springtails.) 

Order 4?k Hemiptera. — Ex. Plant-lice (Aphides), Field-bug (Penta- 
toma), Cochineal Insects (Coccus). 

Order 5 t/ Orthoptera. — Ex. Locusts (Acrydium), Grass-hoppers 
(Gryllus), Crickets (Achetina), Cockroach (Blatta). 
Order 6X Neuroptera. — Ex. White Ants (Termes), Dragon-flies 

(Libellulidae), May-flies (Ephemeridae). 

Order *1. , Aphaniptera. — Ex. Fleas (Pulex). 

Order Diptera. — Ex. Gnats (Culex), Crane-flies (Tipula), House¬ 

flies and Flesh-flies (Musca). 

Order 9. Lepidoptera (Butterflies and Moths). 

Order 10'. Hymenoptera. — Ex. Bees (Apidae), Humble-bees (Bom- 
bidae), Wasps (Vespidae), Ants (Formieidae), Saw-flies 
(Tenthredinidae). 

Order 11. Strepsiptera. — Ex. Stylops. 

Order 12. ColeopLra (Beetles). 


SUB-KINGDOM V.—MOLLUSCA. 

Animal soft-bodied, generally with a hard covering or shell. Nervous 
system consisting of a single ganglion or of scattered pairs of ganglia. A 
distinct heart and breathing-organ, or neither. 

The Mollusca may be divided into the two following primary divisions; 
containing the following classes: 

A. Molluscoida. —Nervous system consisting of a single ganglion or of 
a principal pair of ganglia. No heart, or an imperfect one. 

Class I. Polyzoa. —Animal always forming compound growths or colo¬ 
nies. No heart. The mouth of each zooid surrounded by 
a circle or crescent of ciliated tentacles. — Ex. Sea-mats 
(Flustra), Lace-coral (Fenestella). 


INTRODUCTION. 


21 


Class II. Tunicata. —Animal simple or compound, enclosed in a leathery 
or gristly case. An imperfect heart.— Ex. Sea-squirts 
(Ascidia). 

Class III. Brachiopoda. —Animal always simple ; the body enclosed in 
a bivalve shell. Mouth furnished with two long fringed 
processes or “ arms.”— Ex. Lamp-shells (Terebratula). 

B. Mollusca Proper. —Nervous system consisting of three principal 
pairs of ganglia. Heart well developed, consisting of at least two chambers. 

Class IV. Lamellibranciiiata (Bivalve Shell-fish):—No distinct head ; 

no teeth. Body enclosed in a shell which is “ bivalve,” or 
composed of two distinct pieces. One or two leaf-like gills 
on each side of the body.— Ex. Oyster (Ostrea), Scallop 
(Pecten), Mussel (Mytilus). 

Class V. Gasteropoda. —A distinct heac( and toothed tongue. Shell 
absent in some, but mostly present, and consisting of a single 
piece (“ univalve ”). Locomotion effected by creeping about 
on the flattened under surface of the body (“ foot ”), or by 
swimming by means of a fin-like modification of the same.— 
Ex. Whelks (Buccinum), Limpets (Patella), Sea-lemons 
(Doris), Land-snails (Helix), Slugs (Limax). 

Class VI. Pteropoda. —Animal oceanic, swimming by means of two 
wing-like appendages, one on each side of the head. Size 
minute.— Ex. Cleodora. 

Class VII. Cephalopoda. —Animal with eight or more arms, placed in a 
circle round the mouth. Mouth armed with jaws, and a 
toothed tongue. Two or four plume-like gills. In frbnt of 
the body, a muscular tube (“ funnel ”) through which is ex¬ 
pelled the water which has been used in respiration. An 
external shell in some, an internal skeleton in others.— Ex. 
Calamaries (Loligo), Cuttle-fishes or Poulpes (Octopus), 
Paper-Nautilus (Argonauta), Pearly Nautilus (Nautilus). 


VERTEBRATE ANIMALS. 

SUB-KINGDOM VI .— VER TEBRA TA. 

Body composed of a number of definite segments arranged longitudinally 
or one behind the other. The main masses of the nervous system are placed 
on the dorsal aspect of the body, and are completely shut off from the gen¬ 
eral body-cavity. The limbs (when present) are turned away from that side 
of the body on which the main nervous masses are situated, and are never 
more than four in number. In most cases, a backbone, or “vertebral 
column,” is present in the fully-grown animal 

Class I. Pisces (Fishes).—Breathing-organs in the form of gills; heart 
usually of two chambers, rarely of three; blood cold; limbs, when present, 
converted into fins. 

Order 1. Pharyngobranchii. — Ex. Lancelet (Amphioxus). 

Order 2. MarsipobranchiL — Ex. Lamprey ( Petromyzon ), Hag-fish 

(Myxine). 

Order 3. Tdeostei (Bony Fishes).— Ex. Eels (Muraenidae), Herrings 
(Clupeidae), Salmon and Trout (Salmonidae), Cod and 
Haddock (Gadidae), Flat-fishes (Pleuronectidae), Perch 
(Percidae), Mackerel (Scomberidae). 


22 


INTRODUCTION. 


Order 4. Ganoidei. — Ex. Bony Pike (Lepidosteus), Paddle - fish 
(Spatularia), Sturgeon (Sturio). 

Order 5. Elasmobranchii. — Ex. Sharks (Carcharidae), Dog-fishes 
(Scvlliadae), Saw - fishes (Pristis), Rays and Skates 
(Raiidae). 

Order 6. Dipnoi. — Ex. Mud-fish (Lepidosiren). 

Class II. Amphibia (Amphibians).—Breathing-organs in the young in 
the form of gills alone, afterward lungs, either alone or associated with gills. 
Skull jointed to the backbone by two articulating surfaces (“ condyles ”). 
Limbs never converted into fins. Heart in the young of two chambers 
only, in the adult of three chambers. Blood cold. 

Order 1. Labyrinlhodontia (extinct). 

Order 2. Opkiomorpha. — Ex. Caecilia. 

Order 3. Urodela (Tailed Amphibians).— Ex. Water-newts (Triton), 

Salamanders (Salamandra), Axolotl (Siredon), Mud-eel 
(Siren). 

Order 4. Anoura (Tailless Amphibians).— Ex. Frogs (Rana), Tree- 
frogs (Hyla), Toads (Bufo), Surinam Toads (Pipa). 

Class III. Reptilia (Reptiles).—Respiratory organs in the form of lungs, 
never in the form of gills. Heart three-chambered, rarely four-chambered, 
the pulmonary and systemic circulations always connected together directly, 
either in the heart itself or in its immediate neighborhood. Blood cold. 
Skull jointed to the backbone by a single articulating surface or “ condyle,” 
Each half of the lower jaw composed of several pieces. Appendages of the 
skin in the form of scales or plates. 

Order 1. Chclonia. — Ex. Turtles (Cheloniid)ae, Soft Tortoises (Trio- 
nycidae), Terrapins (Emydidae), Land Tortoises (Tes- 
tudinidae). 

Order 2. Ophidia. — Ex. Vipers (Viperidae), Rattlesnakes (Crota- 
lidae), Sea-snakes (Hydrophidae), Boas and Pythons 
(Boidae). 

Order 3. Lacertilia. — Ex. Lizards (Lacerta), Iguanas (Iguanidae), 
Monitors (Varanidae), Chameleons (Chameleontidae). 

Order 4. Crocodilia. — Ex. Crocodiles, Alligators, Gavials. 

Order 5. lchthyopterygia (extinct).— Ex. Ichthyosaurus. 

Order 6. Sauropterygia (extinct).— Ex. Plesiosaurus. 

Order 7. Pterosauria (extinct).— Ex. Pterodactylus. 

Order 8. Anomodontia (extinct).— Ex. Dicynodon. 

Order 9. Deinosauria (extinct).— Ex. Iguanodon. 

Class IV. Aves (Birds).—Respiratory organs in the form of lungs, never 
in the form of gills. Lungs connected with air-receptacles placed in different 
parts of the body. Heart four-chambered. Blood warm. Skull connected 
with the backbone by a single articulating surface or “condyle.” Each 
half of the lower jaw composed of several pieces. Appendages of the skin 
in the form of feathers. Cavities of the chest and abdomen not separated 
by a complete partition (diaphragm). Fore-limbs converted into wings. 
Animal oviparous. 

Order 1. Natatores (Swimmers).— Ex. Penguins (Spheniscidae), Gulls 
(Laridae), Ducks (Anatidae), Geese (Anserinae), Flamin¬ 
gos (Phaenicopteridae). 

Order 2. GrciUatores (Waders).— Ex. Rails (Rallidae), Water-hens 
(Gallinulae), Cranes (Gruidae), Herons (Ardeidae), Storks 
(Ciconinae), Snipes and Woodcock (Scolopacidae), Plovers, 
Oyster-catchers, and Turnstones (Charadriidae). 


INTRODUCTION. 


23 


Order 3. Cursores (Runners).— Ex. Ostrich (Struthio), American 
Ostrich (Rhea), Emeu (Dromaius), Cassowary (Casu- 
arius), Apteryx. 

Order 4. Rasores (Scratchers).— Ex. Grouse, Ptarmigan, Partridges, 
Pheasants, Turkey, Guinea-fowl, Domestic Fowl, Pea¬ 
fowl (Gailinacei); Doves, Pigeons, Ground-pigeons (Co- 
lumbacei). 

Order 6. Scansorcs (Climbers).— Ex. Cuckoos (Cuculidae), Wood¬ 
peckers (Picidae), Parrots, Cockatoos, Parrakeets 
(Psittacidae), Toucans (Rhamphastidae), Trogons (Tro- 
gonidae). 

Order 6. Insessores (Perchers). — Ex. Crows, Magpies, and Jays 
(Corvidae), Starlings (Sturnidae), Finches, Grosbeaks, 
Larks (Fringillidae), Thrushes, Blackbirds, Orioles 
(Merulidae), Creepers and Wrens (Certhidae), Humming¬ 
birds (Trochilidae), Swallows and Martens (Hirundinidae), 
Swifts (Cypselidae), King-fishers (Alcedinidae). 

Order 7. Raptores (Birds of Prey).— Ex. Owls (Strigidae), Falcons 
and Hawks (Falconidae), Eagles (Aquilina), Vultures 
(V ulturidae). 

Order 8. Saururce (extinct).— Ex. Archaeopteryx. 

Class V. Mammalia (Mammals or Quadrupeds).—Respiratory organs 
in the form of lungs, which are never connected with air-sacs placed in 
different parts of the body. Heart four-chambered. Blood warm. Skull 
united to the backbone by two articulating surfaces or “ condyles.” Each 
half of the lower jaw composed of a single piece. Appendages of the skin 
in the form of hairs. Young nourished by means of a special fluid—the 
milk—secreted by special glands—the mammary glands. Animal vivipa¬ 
rous. 

Non-placental Mammals. —The young not provided with a placenta. 
Order 1. Monotremata. — Ex. Duck-mole (Ornithorhynchus), Spiny 
Ant-eater (Echidna). 

Order 2. Marsupialia. — Ex. Kangaroos (Macropodidae), Kangaroo- 
bear (Phascolarctos), Phalangers (Phalangistida), Opos¬ 
sums (Didelphidae), Tasmanian Devil (Dasyurus). 
Placental Mammals. —The young provided with a placenta. 

Order 3 . Edentata. — Sloths (Bradypodidae), Armadillos (Dasv- 
podidae), Hairy Ant-eaters (Myrmecophagidae), Scaly 
Ant-eaters (Manis). 

Order 4. Sirenia. — Ex. Manatee (Manatus), Dugong (Halicore). 
Order 5. Cetacea. — Ex. Whalebone - whales (Balaenidae), Sperm- 
whales (Physeteridae), Dolphins and Porpoises (Del- 
phinidae). 

Order 6. Unyulata (Hoofed Quadrupeds).— Ex. Rhinoceros; Tapir; 

Horse, Ass, and Zebra (Equidae); Hippopotamus; Hogs, 
and Peccaries (Suida); Camels and Llamas (Camelidae); 
Giraffe; Stags, Elk, Rein-deer (Cervidae); Antelopes 
(Antilopidae); Sheep and Goats (Ovidae); Oxen and 
Buffaloes (Bovidae). 

Order 7. Hyracoidea. — Ex. Hyrax. 

Order 8. Proboscidea. — Ex. Elephants (Elephas). 

Order 9. Carnivora. — Ex. Seals (Phocidae), Bears (Ursidae), 

Raccoons (Procyon), Badgers (Melidae), Weasels and 
Otters (Mustelidae), Civets and Genettes (Viverridae), 


A. 


B. 


24 


INTRODUCTION. 


Order 10. 


Order 11. 


Order 12. 
Order 13. 


Order 14. 


Dogs, Wolves, and Foxes (Canidae); Hyaenas (Hyaeni- 
dae), Cats, Lynxes, Leopards, Tigers, Lions (Felidae). 

Rodeniia. — Ex. Hares and Rabbits (Leporidae), Porcu¬ 
pines (Hystricidae), Beavers (Castoridae), Mice and 
Rats (Muridae), Dormice (Myoxidae), Squirrels and 
Marmots (Sciuridae). 

Cheiroptera. — Ex. Common Bats (Yespertilionidae), 
Horseshoe Bats (Rhinolophidae), Vampire bats (Phyl- 
lostomidae), Fox-bats (Pteropidae). 

Insectivora. — Ex. Moles (Talpidae), Shrew-mice (Soricidae), 
Hedgehogs (Erinaceidae). 

Quadrumana. — Ex. Aye-aye (Cheiromys), Lemurs (Le- 
muridae), Spider-monkeys (Ateles), Howlers (Mycetes), 
Macaques (Macacus), Baboons (Cynocephalus), Gib¬ 
bons (Hylobates), Orang (Simia), Gorilla and Chim¬ 
panzee (Troglodytes). 

Bimana .—Man (Homo Sapiens). 


INVERTEBRATE ANIMALS, 


SUB-KINGDOM L—PROTOZOA. 

CHAPTER I. 

i. General Characters of tiie Protozoa. 2 . Classifica¬ 
tion. 3. Gregarinhle. 

The sub-kingdom Protozoa (Gr. protos , first; and zoon , 
an animal), as the name implies, is the lowest division of the 
animal kingdom, and its limits are therefore necessarily not 
yet strictly defined. The Protozoa comprise an enormous 
number of animals, almost all of which are so small as to be 
invisible to the naked eye, and can only be satisfactorily ex¬ 
amined under pretty high powers of the microscope. For 
this reason, and because they are almost universally found in 
water, these creatures, often popularly called “ animalcules,” 
are almost unknown to the majority of people. Some few, 
however, attain a large size, and of these the sponges are 
familiar examples. The microscopical forms of the Protozoa 
swarm in most stagnant pools, and in all waters charged with 
organic matter so as to afford them food. Every worker with 
the microscope is familiarly acquainted with them, and they 
exhibit phenomena which in many cases render them objects 
of the highest interest. From their low position in the ani¬ 
mal scale, it arises that the Protozoa are mainly characterized 
by the absence of organs and structures which occur in higher 
beings, and they possess few positive characters by which they 
can be distinguished. 

The Protozoa may be defined as animals , generally of 
very minute size , composed of a nearly structureless, jelly-like 



26 


INVERTEBRATE ANIMALS. 


substance {called “ sarcode ”), showing no composition out of 
distinct segments , having no distinct internal cavity , no ner¬ 
vous system , erne? either no organs devoted to digestion , or otf 
a very rudimentary alimentary apparatus. 

Of all the points enumerated in this definition as charac¬ 
teristic of the Protozoa , none is more important than the na¬ 
ture of the body-substance. The body in all known Protozoa 
is composed of a substance which is generally known by the 
name of “ protoplasm ”•—or, better, “ sarcode ” (Gr. sarx , flesh; 
eidos , form)o This sarcode is a gelatinous substance, very like 
white-of-egg to look at. and really of nearly the same chemical 
constitution, consisting mainly of albumen, or of some body 
allied to albumen. Generally, however, it contains numerous 
oil-globules scattered through it. The sarcode shows the phys¬ 
iological property of “ contractility ”—that is to say, under 
appropriate stimuli, or at the will of the animal, it may be 
made to contract or shorten its dimensions, thus giving rise 
to movements. As a rule, no other structures appear in the 
sarcode except minute rounded particles, or granules and 
molecules, but in some cases larger definite structures are 
formed out of it. Of this nature is the so-called “ nucleus ” 
found in many Protozoa. 

As regards their internal structure , some Protozoa exhibit 
nothing worthy of the name of structure at all, the entire 
body being simply composed of sarcode, containing scattered 
granules (for example, the Foraminifera). In other cases 
there are found certain definite bodies which are known as the 
“ nucleus ” and “ nucleolus,” and which are usually, if not 
always, connected with reproduction. Very often, too, there 
are found certain minute cavities or chambers which close and 
expand at definite intervals, and which are known as the 
“ contractile vesicles.” These are, doubtless, rudimentary or¬ 
gans of circulation. In one division of the Protozoa (the In¬ 
fusoria) there is a permanent mouth and a short gullet, but 
in all the others there are no definite organs connected with 
the process of digestion. In no Protozoon , however, without 
exception, have any traces of a nervous system been hitherto 
detected; and in none, even in those which possess a mouth, 
is there any distinct and definite cavity or chamber within the 
body in which the particles of food are received. No organs 
of sense exist in any of the Protozoa —that is to say, there 
are no distinct organs fitted for the reception of impressions 
produced by light or sound; but the general surface of the 
body appears capable of receiving the impressions produced 


PROTOZOA. 


27 


by contact with foreign bodies, and therefore acts as an or¬ 
gan of touch. The power of active locomotion is enjoyed by 
most of Protozoa / but in some cases this is very limited, and 
in other cases the animal is permanently fixed (as in the 
sponges). The apparatus of locomotion in the Protozoa is of 
a varied nature. In many cases, especially in the higher 
forms, movements are effected by means of little hair-like pro¬ 
cesses, which are called “ cilia ” (Lat. cilium , an eyelash), 
and which have the power of vibrating or lashing to and fro 
with great rapidity. In other cases the cilia are accompanied 
or replaced by one or more long whip-like bristles, which act 
in the same fashion, and are known as “ flagella.” Among 
the lower Protozoa the most characteristic organs of locomo¬ 
tion are the so-called “ pseudopodia ” (Gr. pseudos , falsity ; 
podes , feet). These consist of variously-shaped filaments, 
threads, or finger-like processes of sarcode, which the animal 
can thrust out from any or every part of its body. They are 
not, however, definite and permanent organs like the cilia, for 
they can be produced at will, and when they are again with¬ 
drawn they simply melt into the sarcode of the body, and 
leave no traces of their existence. 

As regards the classification of the Protozoa , a rough and 
useful division is into mouth-bearing or “ stomatode ” Proto¬ 
zoa , in which there is a distinct mouth ; and mouthless or 
“ astomatous ” Protozoa , in which there is no mouth. It is 
somewhat doubtful, however, if the mouth-bearing forms 
(namely, the Infusoria) can properly be kept in the Protozoa , 
so that this arrangement is not a very good one. More scien¬ 
tifically, the Protozoa are divided into three great divisions or 
“ classes,” known by the names Gregarinidce , Phizopoda and 
Infusoria , all of which require special examination. 

Class I. Gregarinidce. —The Gregarinidce may be de¬ 
fined as parasitic Protozoa which have no mouth , and have no 
power of giving out pseudopodia. They are usually looked 
upon as forming the lowest class of the Protozoa / but in all 
probability much of their degraded character, as we shall see 
in other cases, is due to the fact that they are internal para¬ 
sites, and are therefore not dependent on their own exertions 
for food. They vary in size from less than the head of a small 
pin up to nearly half an inch in length, when they look some¬ 
thing like small worms ; and they are found inhabiting the in¬ 
testines of various animals, especially the cockroach and the 
earthworm. 


28 


INVERTEBRATE ANIMALS. 


In anatomical structure a Gregarina usually presents the 
appearance of a single cell, consisting of an ill-defined mem¬ 
branous envelope, tilled with a more or less granular sarcode 
containing fatty granules, and having in it a little central 
bladder or vesicle—the “ nucleus ”—which in turn encloses a 
solid particle or “ nucleolus ” (Fig. 2, a). The outer covering 



Fig. 2. —Anatomy and reproduction of the Gregarina of the earthworm (after Lieberkiihn) 
a Adult Gregarina; & The same “encysted;” c With the contents broken up into 
pseudonayieellae ; d Free pseudonavicellae ; e Contents of the pseudonavicellae when lib¬ 
erated. 

or cuticle with which the protoplasmic body is enclosed may 
be quite smooth, or it may be furnished with bristles or 
spines, and in some cases even cilia have been observed. Be¬ 
yond the nucleus and nucleolus (which are probably connected 
with reproduction), no definite organs have been detected in 
the Gregarhicv; and all the processes of assimilating food 
and getting rid of waste or injurious products must be effected 
by the general surface of the body. As we shall see, how¬ 
ever, this is common in internal parasites, which are not 
necessitated to live upon solid food, but which are enabled to 
subsist simply by imbibing the nutritive juices of their hosts. 

The following is a brief outline of the process of reproduction as it has 
been observed in the Gregarince, sometimes in a single individual, some¬ 
times in two individuals which have come together and completely coalesced 
and melted into one another. The Gregarina becomes completely motion¬ 
less, assumes a globular form, and develops round itself a thick structureless 
coat or envelope, when it is said to be “ encysted ” (Fig. 2, b). The nucleus 
then disappears, and the sarcode of the body breaks up into little masses, 
which are at first rounded, but afterward become pointed at both ends, when 
they are called “ pseudonavicellae ” (Fig. 2, c). The cyst then breaks and 
the pseudonavicellae escape, when they give origin to little masses of sar¬ 
code, which have the power of active movement and of throwing out pseudo¬ 
podia, thus coming closely to resemble the animalcule which will be directly 
described as the Amoeba (Fig. 2, e). These little amoeba-like masses, if they 
find a suitable locality, are finally developed into new Gregarince. 




CHAPTER II. 

Rhizopoda. 

The next class of the Protozoa which we have to consider 
comprises the most characteristic and typical forms of the 
whole sub-kingdom. The name of Rhizopoda , or “root¬ 
footed ” animalcules (from the Greek, rhiza , root; and podes , 
feet), is derived from the fact that they all possess the power 
of throwing out at will from various parts of the body the 
processes ot sarcode which have been already spoken of as 
pseudopodia, and by which they both move and obtain food. 
In fact, the Rhizopoda may be shortly defined as Protozoa 
which have no mouth and possess the power of giving out 
pseudopodia. The pseudopodia vary a good deal in shape 
and in other characters in different orders of the Rhizopoda , 
but they have invariably the character of being nothing more 
than temporary threads or finger-like processes of sarcode, 
which can be thrust out at will, and which melt again into the 
substance of the body when they are withdrawn. 

Five distinct types of structure are known in the Rhizo- 
poda, and these constitute as many distinct orders, w’hich are 
known by the names of the 3Ionera , Amoebea , Foraminifera , 
Radiolaria , and Spongida. 

Order I. Monera. —This name lias been proposed for a 
small group of organisms which merely require to be men¬ 
tioned. They are all microscopic in size, and inhabit the sea. 
Their sarcode-body is entirely structureless and devoid of defi¬ 
nite organs of any kind. They have the power, hovvever, of 
throwing out innumerable processes of the body-substance or 
“ pseudopodia,” and these agree in their characters with those 
which will be afterward described as characterizing the Fora¬ 
minifera. They are, namely, very long and delicate filaments 
of sarcode, which unite in various directions so as to form a 
net-work, in which the particles of food are entangled. The 
body is completely naked, and the Monera differ from the 


30 


INVERTEBRATE ANIMALS. 


Foraminifera , chiefly if not entirely, in this absence of any 
hard covering or shell. 

Order II. Amcebea. —This order is characterized by the 
fact that the pseudopodia are mostly blunt and finger-like in 
shape , and that the sarcode of the body contains the structures 
known as the “ nucleus ” and “ contractile vesicle .” 

As the type of the order may be taken the Amoeba or Pro- 
teus-animalcule, so called because of the incessant and illimit¬ 
able changes of form which it exhibits (Gr. amoibos , chan¬ 
ging). The Amoeba is a little microscopical creature which 
may commonly be detected in stagnant water, especially 
where there is decaying vegetable matter. When examined 
under the microscope, all that would probably be seen at first 
would be a shapeless or irregularly-spherical mass of gelati¬ 
nous, jelly-like sarcode, containing scattered granules. Soon 
the creature might be observed to push out a finger-shaped 
prolongation of its own substance ; and it w T ould soon be 
found that similar processes or pseudopodia could be pushed 
out at will from almost any point of the body and again re¬ 
tracted within it without leaving any trace behind. As a 
result of this, the form of the animal is constantly changing, 
and hence its common name of Proteus-animalcule (Fig. 3, a). 
By means of these temporary processes of sarcode, the Amoeba 




Fig. 3. —Morphology of Rhizopoda. a Amoeba radiosa , showing the pseudopodia, the 
contractile vesicle, nucleus, and vacuoles; b Difflugia , with the pseudopodia protruded 
from the anterior end of the carapace; c Detached sponge-particles or “ sarcoids; ” 
d Ciliated sponge-particles of Grantia; e Sponge-particle of the fresh-water sponge 
(Spongilla) with a single cilium. 

both moves and obtains food. Locomotion is effected in a 
kind of creeping manner, the animal pushing out the pseu¬ 
dopodia in one direction and then pulling the body in the 
same direction. In the same way, when any minute particle 
of food, such as a microscopic plant, comes within its reach, 
the Amoeba wraps a pseudopodium round it, and then with¬ 
drawing the pseudopodium, lodges the nutrient particle se 


RIIIZOPODA. 


31 


curely in the substance of the body. It follows from this that 
the Amoeba has no permanent mouth—no aperture, that is, 
which is especially employed in the admission of food. Any 
part of the surface can be pushed out into a pseudopodium, 
and therefore any part of the surface can be extemporized 
into a mouth. The process of taking 1 food, in fact, in the 
Amoeba, has been aptly compared to thrusting a stone or any 
other solid bpdy into a lump of dough. The central portion 
of the body of the animal is softer and more fluid than the 
outer layers, and the particles of food, on reaching this point, 
undergo a sort of digestion, and are subjected to a species of 
movement or rotation in the interior of the animal. Each 
particle of food, in the process of 'being taken into the body, 
usually carries with it a little drop of water; and in this way 
a number of clear spaces are formed, which are usually quite 
round, and look like distinct cavities. These spaces are called 
“ vacuoles; ” but they are not distinct organs of any kind, 
though formerly regarded as distinct stomachs. Having un¬ 
dergone digestion, any portions of food which may be indigest¬ 
ible or insoluble are simply thrust out again through the walls 
of the body. This appears to be effected at one particular 
part of the body ; but there is no permanent aperture for the 
purpose. There are no distinct vessels which serve to convey 
the nutritive fluid derived from the digestion; but there does 
appear to be a rudimentary organ by which this fluid is driven 
through the body. If we watch an Amoeba carefully, there is 
usually no difficulty in observing that every now and again 
there appears at one particular place a clear spot, “ like a 
window,” which slowly expands to its full extent, and then 
usually contracts slowly till it disappears altogether. This 
process of gradual expansion and contraction is what is called 
“ rhythmical ”—that is to say, it is repeated at tolerably regu¬ 
lar intervals, perhaps twice a minute. In some cases the 
vesicle, when contracted, remains so for a long time, but it 
always reappears in the same place. It is known as the con¬ 
tractile vesicle; and there can be little doubt that it is a 
permanent organ. It is, in fact, a little clear space or cavity 
in the substance of the body, filled probably with the nutri¬ 
tive fluid derived from the digestion, and no doubt serving by 
its contraction to drive this fluid to various parts of the body. 
In its function, then, the contractile vesicle of the Amoeba is 
to be looked upon as the first indication which we have in the 
entire animal kingdom of that most important organ, the 
heart. 


32 


INVERTEBRATE ANIMALS. 


The Amoeba possesses no breathing-organs, of any kind, 
and no excretory organs, so that these functions must be per¬ 
formed by the general surface of the body in a manner some¬ 
what the same as the exhalation from the skin which takes 
place in the higher animals. There are also no traces of a ner¬ 
vous system, and no organs of sense, and the only other struct¬ 
ure of any kind is what is known as the nucleus. The nucleus 
is simply a small rounded or oval granular mass, and there may 
be more than one in the same individual. Its function, how¬ 
ever, is quite unknown, though it is probably connected with 
reproduction. The means employed by the Amoeba to per¬ 
petuate the species are various, but the only one which need 
be mentioned is the process by self-division. This is what is 
technically called “ fission ” (Lat findo , I cleave), and it con¬ 
sists in a gradual division or cleavage of the body into two 
parts, each of which then becomes a separate and independent 
individual. In some cases this process is slightly varied, a 
single pseudopodium alone being cast off and becoming a 
fresh Amoeba , but this does not differ essentially from the for¬ 
mer. 

Regarding the Amoeba from a physiological point of view, 
we see that, though the animal nourishes itself and maintains 
its existence perfectly, the process of nutrition is carried on in 
the simplest possible manner and with the simplest possible 
apparatus. There is no permanent mouth, no stomach or ali¬ 
mentary canal of any kind, no respiratory or excretory organs, 
and even no distinct aperture for the extrusion of indigestible 
food. The only distinct structure which is at all concerned in 
nutrition is a rudimentary contractile cavity, the first foreshad¬ 
owing of the heart in the higher animals. As regards the 
functions of relation, it is questionable how far the Amoeba 
can be said to have distinct perceptions or sensations of any 
kind. It has no nervous system or organs of sight or hearing, 
and in all probability it has nothing more than a general sen¬ 
sibility to light. It appears, however, to be fully aware when 
any object comes in contact with a pseudopodium, and even 
to have some idea whether this is fit for food. Locomotion, 
as we have seen, is entirely effected by the temporary pro¬ 
cesses of sarcode or pseudopodia, and there are no permanent 
organs set aside either for locomotion or for prehension—that 
is, for seizing external objects. 

The only other member of the Amoebea which deserves 
notice is the Difflugia (Fig. 3, 6), which is not uncommonly 
found in fresh water. Difflugia in its essential structure 


RH1Z0P0DA. 


33 


does not differ from the Amoeba , but the greater part of the 
body is enclosed in a sort of case or carapace, mostly com¬ 
posed of grains of sand, within which the animal can retire 
completely. The carapace is open at one end, and the pseu¬ 
dopodia are protruded from this aperture. The animal gene¬ 
rally creeps about head-downward, so to speak; that is to say, 
with the closed end of the carapace elevated above the surface 
on which it is moving. 

Order III. F oraminifera (Lat. foramen , an aperture; 
fero, I carry). —The next order of the Bhizopoda is that of the 
Foraminifera , comprising animals which at first sight appear 
to be highly complex, but which are really much less highly 
organized than the Amoeba. The Foraminifera may be de¬ 
fined as Bhizopoda in which the body is protected by a shell 
or “test;” there is no nucleus or contractile vesicle ; and the 
pseudopodia are extremely long and threadlike , and interlace 
with one another so as to form a net-work. 

The most obvious and striking character of the Forami¬ 
nifera is the possession of an outer case or shell, and for a long 
time they were known to naturalists by their shells alone. As 
the shell or test is usually very beautiful and often very com¬ 
plex, the Foraminifera were consequently placed at first 
among the true shell-fish (. Mollusca :), very much in advance of 
their true position. When, however, the anatomical structure 
of the group came to be investigated, it was soon found that 
they were really referable to the Protozoa , and that in point 
of fact they even occupy a low position in this sub-kingdom. 
However elaborate and complicated the shell may be, the body 
of the contained animal is composed simply of granular gelati¬ 
nous sarcode, highly elastic and contractile, and usually red¬ 
dish or yellowish in color. This sarcode not only fills the 
shell, but also in many cases gains the exterior by means of 
little perforations in its walls, and forms a thin film over its 
outer surface. Wherever the sarcode is exposed, whether this 
be only at the mouth of the shell, as in Miliola (Fig. 4, 5), or 
whether it be over the whole surface, as in Discorbina (Fig. 4, 
c), it has the power of giving off pseudopodia. The pseudo¬ 
podia, however, differ greatly from those of the Amoeba , and 
they show some remarkable characters. They are extremely 
long, threadlike processes, instead of being blunt and finger- 
shaped, and they have the curious property that they run into 
one another and interlace toward their extremities, so as to 
form a net-work which has been aptly compared to an “ ani- 


34 


INVERTEBRATE ANIMALS. 


mated spider’s web.” Lastly, the microscope reveals in the 
pseudopodia a very curious circulation of minute solid parti¬ 
cles or granules, which travel in all directions through the 
pseudopodial net-work. Internally, the sarcode-body of the 
Foraminifera exhibits absolutely no structures or definite or¬ 
gans of any kind. Even the nucleus and contractile vesicle 
which occur in the Amoeba are here absent, and the only traces 
of structure are to be found in the existence of scattered gran¬ 
ules. 

Simple as is the sarcode-body of the Foraminifera , it has 
in all cases the power of secreting a skeleton or shell, which 
is technically called the “test” (Lat. testa, a shell). The 
shell is usually “ calcareous ”—that is to say, composed of car¬ 
bonate of lime; but it is sometimes “ arenaceous,” or com¬ 
posed of particles of sand united together firmly by an un¬ 
known animal cement. In either case, the shell may exhibit 
one or other of two very distinct types of structure. In the 
one type (as in Miliola , Fig. 4, b), the shell-walls are not per- 



Fig. 4.— Morphology of Foraminifera. a Lagena vulgaris, a monothalamous Foraminifer- 
b Miliola (after Schultze), showing the pseudopodia protruded from the oral aperture of 
the shell; c Discorbina (after Schultze), showing the nautiloid shell with foramina in 
the shell-walls, giving 1 exit to pseudopodia \ d Section of Nodosciviu (after Carpenter) * 
e Nodosaria hispida ; f Globig&rina bulloides. ' 

forated with holes, and the pseudopodia are therefore all 
emitted from the mouth of the shell. In the other type (as in 




RHIZOPODA. 


35 


Discorbina, Fig. 4, c) the shell-walls are perforated with a 
number of little apertures or “ foramina,” from which the or¬ 
der derives its name. These foramina are the mouths of 
tubes which pierce the walls of the shell, and thus establish 
a free communication between the interior and exterior. In 
this way the sarcode which fills the inside of the shell is en¬ 
abled to reach the outer surface, so as to form a film, from 
any part of which the pseudopodia may be given off. The 
presence or absence of foramina is believed to constitute a 
true structural distinction, and the Foraminifera may be 
thereby divided into two great groups ( Perforata and Ini- 
perforata). 

According to the form of the shell, also, the Foraminifera 
may be conveniently, though arbitrarily, divided into two 
great sections. The simplest form of shell is seen in such an 
example as Lagena (Fig. 4, a ), where the shell consists of but a 
single chamber; and the animal, in fact, is nothing more than 
a little mass of sarcode, surrounded by a calcareous envelope. 
Lagena , then, may be taken as the type of what are called 
the “ monothalamous ” Foraminifera (Gr. monos , single; 
thalamos , a chamber)—that is to say, of those forms in w’hich 
the animal consists of a single segment, and the shell of a 
single chamber. All the Foraminifera without exception 
commence life as “ simple ” or “ monothalamous ” forms, like 
Lagena , but it is comparatively seldom that they retain this 
simplicity throughout life. In the great majority of cases the 
primitive mass of sarcode commences a process of budding, 
or “ gemmation,” by which it becomes converted from a “ sim¬ 
ple ” into a “ compound ” form. The original sarcode-mass, 
that is to say, begins to throw out buds in some determinate 
direction; all the buds thus produced remaining connected 
with one another, and all surrounding themselves with a cal¬ 
careous covering. In this way we get ultimately a compound 
organism, composed of a number of little masses of sarcode, 
all permanently united to one another, and all enclosed in a 
common shell. We get then, ultimately, such a form as JVo- 
dosaria (Fig. 4, d , e), which may be regarded as a good example 
of these so-called “ compound ” or “ polyihalamous ” Fora - 
minifera (Gr. polus, many; thalamos , a chamber). The exact 
form of shell which is produced by this process of budding 
will depend upon the direction in which the buds are given 
off by the primordial segment. If the buds are given off in a 
line, we get such a form as Nodosaria. If they are given off 
in a spiral direction, each succeeding segment being a little 


36 


INVERTEBRATE ANIMALS. 


larger than the one before it, and the coils of the spiral all 
lying in one plane, then we get such a shell as Discorbina 
(Fig. 4, c). This is one of the commonest forms of shell among 
the Foraminifera , and it is often called the u nautiloid ” shell, 
from the close resemblance which it bears in shape to the 
well-known shell of the pearly Nautilus. It was, in fact, this 
external similarity which induced the older naturalists to 
place the Foraminifera among the Mollusca in the neighbor¬ 
hood of the cuttle-fishes. There are numerous other types of 
s v iell, all of which can be referred to the manner in which 
gemmation is carried on by the primordial segment; but the 
two forms above mentioned may be. taken as sufficient ex¬ 
amples. It may be mentioned, however, that there are forms 
in which the new segments are added in a very irregular man¬ 
ner, and the resulting colony has no very definite shape, as in 
Globigerina (Fig. 4,/*). 

Affinities of the Foraminifera. —In spite of their beautiful, and in 
many cases complex, shells, the anatomical structure of the Foraminifera is so 
simple that it may fairly be questioned whether in a systematic arrangement 
they should not be placed at the bottom of the whole sub-kingdom Protozoa. 
Perhaps the nearest relatives of the Foraminifera are the Polycystina, a 
group of organisms which we have yet to consider. These differ from the 
Foraminifera in little or nothing, except that the shell is composed of flint. 
The Foraminifera are also clearly related to those forms of the Amcebea 
which possess shells, such as Difflugia. The sarcode-body of Difflugia , 
however, contains a nucleus and a contractile vesicle, and the pseudopodia 
are thick and blunt, so that the differences are sufficiently weighty. There 
are also very interesting points of relationship between the Foraminifera 
and the sponges, which cannot be touched upon here. A few words, how¬ 
ever, may be said on the physiological deductions which may be drawn from 
the study of the Foraminifera. Regarded from a physiological point of 
view, the structural simplicity of the Foraminifera renders them all the 
more wonderful. We have in them the great equation of life presented to 
us in perhaps its simplest form. They are composed of an organic substance, 
but cannot be said to possess “ organization,” being “ structureless, and 
without permanent distinction or separation of parts.” * Nevertheless they 
perform all the physiological functions ; they assimilate food—they live, 
grow, and maintain their integrity in the face of the destructive forces con¬ 
stantly at work upon them—they reproduce their like—and they have cer¬ 
tain relations with the external world, being at any rate capable of indepen¬ 
dent locomotion. All these vital actions they effect without possessing a 
single organ permanently set apart for the performance of any one of them. 
Lastly, they have the power of building up an outer envelope or shell, which 
is always beautiful, and is often of the most complex character, and con¬ 
structed upon a regular mathematical plan. The Foraminifera , then, of all 
known animals, offer the most convincing illustration of two laws : firstly, 
that there is something in the action and nature of vital forces altogether 
distinct from any thing hitherto observed in the physical forces ; and sec- 


* Huxley. 


RIIIZOrODA. 


37 


ondly, that life is the cause of organization, and not the result of it: in other 
words, an animal is organized, or possesses structure, because it is alive; it 
does not live because it is organized. 

Distribution of Foraminifera in Space.* —The Foraminifera are ex¬ 
clusively marine or inhabitants of the ocean, and have a world-wide distribu¬ 
tion. They are mostly very minute, but some of the extinct forms attained 
a size of as much as three inches in circumference (e. g., the Nummulite, 
Fig. 5). Some forms may be obtained adhering to the roots of tangle (Lami- 
niria) at or near low-water mark, but they are mostly to be dredged from tol¬ 
erably deep water. In the deepest parts of the ocean which have yet been 
examined by the dredge—at a depth, namely, of nearly three miles— Forami- 
uifera have been obtained in abundance. There is also no doubt that in 
many parts of the deep ocean, especially where warm currents exist, there 
are now forming deposits of the shells of Foraminifera , which may well be 
compared to the great masses of white chalk with which the geologist is 
familiar. Foraminifera may generally be obtained for examination from the 
shakings of sponges or from the sand of the sea-shore, especially in warm 
climates. To give some idea of their abundance, it may be stated that Plan- 
cus found about 6,000 specimens in an ounce of sand from the Adriatic ; but 
D’Orbigny calculated that no fewer than between three and four millions 
were present in an ounce of sand from the Caribbean Sea. 

Distribution of Foraminifera in Time. —It is not the object of the 
present work to enter into the consideration of the past existence of differ¬ 
ent groups of animals, since this presupposes some knowledge of geology, 
but the Foraminifera present some points of special interest which may be 
very shortly noticed. In the first place, as far as is yet known, the Forami¬ 
nifera were the earliest and oldest of created beings. The oldest fossil 
which has hitherto been exhumed by the labors of geologists is believed to 
have been a Foraminifer , f of large size, and with some decided affinities to 
existing forms. In the second place, it is only by an examination of the dis¬ 
tribution of the Foraminifera in past time that we can arrive at any ade¬ 
quate notion of the importance of these microscopic creatures when looked 
at in the aggregate. The great geological formation known as the white 
chalk—a formation which forms the well-known chalk-cliffs of the south of 
England, and which stretches over a great part of the continent of Europe, 
attaining sometimes a thickness of not less than 600 feet—is almost wholly 
composed of the shells of Foraminifera, visible only to the microscope. The 
smallest fragment of the common chalk, with which every one is familiar, 
contains numbers of these minute shells; and it is a singular fact that some 
of the species in the chalk are indistinguishable from forms which now oc¬ 
cur in the ooze which forms the bed of the Atlantic at great depths. The 
stone of which Paris is built is to a very great extent composed of the shells 
of Foraminifera , especially of the Miliola ; and it is hardly an exaggeration 
to say that Paris is mainly built up out of these minute organisms. Another 
remarkable formation is that known as the “Nummulitic limestone,” from 
the presence in it of a large coin-shaped Foraminifer , the Nummulite (Fig. 
o), generally about as large as a shilling. 

The Nummulitic limestone stretches from France on the west to the fron¬ 
tiers of China on the east, and is almost everywhere readily recognizable as 

* Under the term “ Distribution in Space” come all the facts relating 1 to the present 
occurrence of any animal or group of animals upon the globe. Under the term “Distribu¬ 
tion in Time ” come all the facts relating to the past occurrence of any animal or group of 
a lima Is upon the globe. 

+ The Eozoon Cana dense of the Laurentian Docks of Canada. 

3 


38 


INVERTEBRATE ANIMALS. 


a distinct formation. It attains in places a thickness of several thousand 
feet, and is especially largely developed in the Alps.* It has an historic in¬ 
terest from the fact that the Pyramids are built of it, and that the Nummu- 
lites in it were noticed by Herodotus, the “ father of history.” 



Fig. 5. —Nummulites Ic&vigatus. 


Order IV. Radiolaria (Lat. radius , a ray).—The third 
order of the Rhizopoda is that of the Radiolaria , essentially 
distinguished by the fact that the sarcode-body has the power 
of secreting a “ siliceous ” or flinty skeleton, either in the form 
of a shell, or of detached spicules or needles; while the pseu¬ 
dopodia are long and thread-like, and stand out from the body 
like rays. In this last character the Radiolaria approach 
very closely to the Foraminifera; and the resemblance be¬ 
tween the two groups is still further increased by the fact 
that the pseudopodia often run into one another so as to form 
a net-work, and sometimes show a circulation of granules 
along their edges. Three groups of organisms have been 
described as belonging to the Radiolaria , and we may briefly 
notice an example of each of these. 

In the first family we have organisms like AcantTiometra 
(Fig. 6, a), in which the body is composed of sarcode, sup¬ 
ported by a framework of siliceous or flinty rods, which all 
meet in a common centre. The spines or rods are all perfo¬ 
rated by canals, and each conveys a pseudopodium, which is 
protruded from an aperture at its apex. Many pseudopodia, 
however, are given off from the surface of the body directly, 
and are not enclosed in the spines. The Acanthometrce are 
all minute, and are found floating near the surface in the open 
ocean, sometimes in great numbers. 

In the second family ( Polycystina , Fig. 6, b) we have a 
number of beautiful little organisms closely allied to the Fo¬ 
raminifera, but differing in the fact that the body is enclosed 
in a glassy shell composed of flint. The shell is perforated 
by numerous holes through which the pseudopodia are 
emitted, and it is usually of extreme beauty, being sculptured 


RHIZOPODA. 


39 


in various ways, and often adorned with spines. The sarcode 
of the body is usually olive brown in color, and often does 
not quite fill the shell. 



Fig. 6. —a Acanthometra lanceolcita; 6 TTaliomma hexacanthwm , one of the Polycys- 
tina (after Muller). 

The pseudopodia are filamentous, and exhibit a slow cir¬ 
culation of granules along their borders, but they do not run 
into one another. All the Polycystina are microscopic, and 
they are all inhabitants of the sea. They are best known to 
students of the microscope as the “Fossil Infusoria of Barba- 
does,” as they occur in incalculable numbers in a sandstone in 
that island. 

In the third family ( Thalassicollida , Fig. 7) are included 
a number of singular gelatinous organisms which may be as 
large as an ordinary marble, but are often hardly visible to 
the unassisted eye. They are found floating passively at the 
surface of most seas. 

The body in all the Thalassicollida is composed of sarcode, 
and has the power of giving off thread-like radiating pseudo¬ 
podia, which sometimes run into one another and form net¬ 
works. In all cases the sarcode-body appears to have the 
power of secreting flint in some form or other. In Collo- 
sphcera (Fig. 7, «), the flint is secreted in the form of a shell 
or test, perforated by large apertures. In Thalassicolla (Fig. 
7, b), the silica forms groups of needles or “spicula,” scattered 
here and there in the jelly-like sarcode. 

Order IV. Spoxgida. —The last order of the Phizopoda 
is that of the Spongida , the exact nature and position of 
which have only recently been determined. For a long time 
sponges were pretty generally regarded as being vegetables, 
and it is only since the microscope has been employed in their 










40 


INVERTEBRATE ANIMALS. 


elucidation that their true nature has been made out. Most 
naturalists are now agreed as to the propriety of placing the 
sponges in the animal kingdom, and they are generally re¬ 
ferred to the Bhizopoda , though they are sometimes looked 
upon as constituting a distinct and separate class of the Bro- 
tozoa. The apparent complexity ol structure which the 
sponges exhibit is due to the fact that what we ordinarily 



f 1Gi 7,_ a Siliceous shell of Collorphcera ; b Thalassicolla , showing the radiating pseud®- 

podia and groups of siliceous spicula (after Muller). 

term a sponge is really a colony or aggregation of separate 
masses of sarcode, greatly resembling Amoebae in structure, 
and having the power of secreting a skeleton or supporting 
framework common to the whole assemblage. Sponges, in 
fact, may be defined as compound Bhizopoda , forming 
masses which are traversed by canals opening on the surface , 
and supported by a framework of horny fibres or of calcare¬ 
ous or flinty needles. 

There are, then, two essential elements in the structure of 
a sponge—namely, the sarcode-bodies which constitute the 
animal itself, and which are collectively termed the “ sponge- 
flesh,” and the hard framework or “ skeleton ” upon which the 
flesh is supported. To understand the nature of these fully, 
we may take an ordinary horny sponge, such as we are con¬ 
stantly in the habit of using. As we see the sponge in this 
country, we are only acquainted with the skeleton, which is 
composed of an enormous number of horny fibres, all interlaced 
and interwoven with one another, but leaving numerous holes 
and canals between their bundles (Fig. 9, d). In its living 
condition, however, the whole of this skeleton is covered in¬ 
side and outside—saturated, in fact—with a kind of slimy ma¬ 
terial very like white-of-egg to look at. This is the so-called 
sponge-flesh, and, upon examining this with a microscope, it 
is found to be composed of an enormous number of minute 


RIIIZOPODA. 


41 


masses of sarcode, all more or less completely independent 
of each other, and each very closely resembling an Amoeba . 
These separate “ sponge-particles,” or “ sarcoids,” as they are 
called, consist, in fact, of granular sarcode, capable of pushing 
out little processes or threads of sarcode in the form of pseudo¬ 
podia, and sometimes furnished with an internal solid mass or 
nucleus (Fig. 3, c ). In some cases each sarcoid carries a 
single lash-like vibrating filament or cilium (Fig. 3, d , e ). 
Each sarcoid has the power, if detached, of independent move¬ 
ment, and each can obtain food for itself. As the sponge, 
however, is a fixed animal, some provision is necessary by 
w’hich food shall be conveyed to the sarcoids in the interior of 
the mass. This is effected by a remarkable water-carrying or 
“aquiferous” system in the following manner: The entire 
sponge is riddled in every direction by an immense number 
of canals, all opening on the surface, and communicating freely 



Fig. 8 .—Diagrammatic section of Spongilla (after Huxley), a a Outer or superficial layer 
of the sponge; b b Inhalant apertures, or “ pores;” c c Ciliated chambers; d An exha- 
lant aperture, or “ osculum.” The arrows indicate the direction of the currents. 

with one another in the interior of the mass. The canals are 
of different sizes, and, as can readily be observed in an ordinary 
sponge, their external openings are also of different sizes. A 
few of the holes are of much larger size than the others, and 
these, for reasons which will be seen directly, are called the 
“ exhalant apertures,” or “ oscula.” The great majority of the 
holes are very minute, and these are known as the “ inhalant 
apertures,” or “ pores.” In a living sponge a more or less 
constant circulation of water is carried on by means of this 
canal system. The water is admitted by means of the pores 
(Fig. 8, b 5), is driven into the interior of the sponge, and is 
finally expelled in steady streams from the oscula (Fig. 8, d). 
The mechanism by which this circulation of water is effected, 


42 


INVERTEBRATE ANIMALS. 


was long unknown, but it is now known to consist in aggrega¬ 
tions of sponge-particles provided with cilia which all work 
toward the interior of the sponge (Fig. 8, c c). The circula¬ 
tion of water in this manner can be readily observed in many 
of our common marine sponges, and it is under the control of 
the animal to a great extent. The large apertures or oscula 
are permanent, but they can be closed and opened at will; 
while the smaller apertures or pores appear to be formed 
afresh, wherever they are wanted, at any point of the surface. 
By means of the currents of water each individual sarcoid or 
sponge-particle is enabled to obtain food, so that the whole 
sponge, as remarked by Huxley, “ represents a kind of sub¬ 
aqueous city, where the people are arranged about the streets 
and roads in such a manner that each can easily appropriate 
his food from the water as it passes along.” It is also not 
improbable that the process is at the same time a rudimentary 
form of respiration. 



Fig. 9. —a Gemmule of Spongilia; h Hilum; & Diagrammatic section of the gemmule> 
showing the outer layer of spicules or amphidiscs, and the inner mass of cells; h Hilum; 
c One of the amphidiscs seen in profile; d Fragment of the skeleton of a horny sponge 
(after Bowerbank), showing the interlacing horny fibres with spicula. All much magni¬ 
fied. 

Such, then, are the general phenomena exhibited by any 
sponge, and the chief variations which occur among the 
sponges are to be found in the nature of the skeleton. In the 
sponges of commerce the skeleton consists of matted fibres 
composed of a substance nearly allied to horn. In other forms 
the skeleton is calcareous, or composed of lime; and in other 
cases, again, it is siliceous, or composed of flint. The Venus’s 
flower-basket (Euplectella), which looks like a goblet woven 





RIIIZOrODA. 


43 


of spun glass, is a familiar example of the flinty sponges. In 
most cases, the skeleton, and often the flesh as well, is fur¬ 
nished with more or less numerous needles or spicula, gener¬ 
ally of flint, but sometimes of lime, which assume a great vari¬ 
ety of shapes, and appear to exercise different functions (Fig. 
9, c, d). 

As regards the reproductive process in the sponges, it will 
be sufficient to state very briefly the leading phenomena which 
have been observed in the fresh-water sponge ( Spongilla 
flumatilis). If a specimen of Spongilla be observed toward 
the approach of winter, its deeper portions will be found to be 
filled with numerous small, rounded bodies, like seeds, which 
have been called u gemmules.” Each gemmule (Fig. 9, &, b) 
exhibits at one point a small aperture, and is found to be com¬ 
posed of a leathery membrane, surrounded by a layer of sar- 
code, in which are imbedded a number of spicula. These 
spicula consist each of a central rod or axle carrying a toothed 
wheel or disk at each end (Fig. 9, c). In the interior of the 
capsule thus formed is a mass of cells, of which the central 
ones contain numerous reproductive germs. When the spring 
comes, these masses are discharged into the water through the 
aperture of the gemmule, and become developed into fresh 
Spongillce. In addition to this method of reproduction, the 
fresh-water sponge during the summer months has the power 
of producing true eggs or ova, and sperm-cells. The impreg¬ 
nated ova develop themselves into embryos, which are pro¬ 
vided with numerous cilia or vibrating hairs, by means of 
which they swim about freely. Finally, upon finding a suit¬ 
able locality, they fix themselves to some solid object, lose 
their cilia, and grow up into Spongillce. Indeed, as a general 
if not universal rule, the embryos of the sponges are provided 
with cilia, and are thus capable of active locomotion. In this 
way is secured the extension over a wide area of these other¬ 
wise fixed and plant-like organisms. 

Distribution of Sponges in Space. —It remains only to add 
a few words on the distribution of sponges in space. With 
the single exception of Spongilla , all known sponges are in¬ 
habitants of the sea; but the former is to be found in lakes 
and rivers in most parts of the world. Tiie marine sponges 
are found mostly attached to stones and other foreign objects 
between tide-marks and in deep water. The sponges of com¬ 
merce are mostly obtained from the Grecian Archipelago, but 
inferior kinds are imported from the Bahama Islands. One 
common sponge ( Cliond ), instead of incrusting other objects, 


44 


INVERTEBRATE ANIMALS. 


inhabits branching cavities in shells, which it excavates for 
itself. It apparently lives upon the animal matter contained 
in the shell, and few oyster-shells can be picked up upon our 
shores which do not exhibit the perforations and mines of 
some species of other of this genus. Fossil shells, also, often 
occur, wdiich show that these mining sponges have enjoyed a 
vast antiquity. 


CHAPTER IIL 


Intusoria. 

The last class of the Protozoa is that of the Infusoria , so 
called because of their being frequently developed in organic 
infusions under the following singular circumstances: If some 
water be taken, and any animal or vegetable substance be 
soaked or boiled in it, a solution is formed containing organic 
matter, or, in other words, an “ organic infusion.” It is un¬ 
necessary to say that if this infusion be examined under the 
microscope, after boiling, nothing will be detected in it— 
nothing living, at any rate. If examined, however, at the end 
of a few days’ time—if the circumstances have been favor¬ 
able—a vast number of living forms will now be found in it. 
Among these will be found several of the members of the 
present class, and hence the name applied to them of Infusorian 
animalcules, or Infusoria . It is unnecessary to enter here 
into the question how these living beings are produced, since 
the subject is one of great obscurity, and opinions are still 
divided upon it. It is sufficient to remark that there are emi¬ 
nent observers who hold that the appearance of the Infusoria 
in this fashion is to be explained upon the theory that they 
have been spontaneously produced out of the inorganic ma¬ 
terials of the infusion, in opposition to the general view that 
they are derived from preexistent germs. 

The position of the Infusoria is somewhat doubtful, and 
it appears probable that they will ultimately have to be re¬ 
garded as a separate sub-kingdom, or as a branch of a higher 
sub-kingdom (Annuloida). In the mean while it is most con¬ 
venient to retain them in their present place, at the head of 
the sub-kingdom Protozoa . Regarded in this light, the In¬ 
fusoria present a great advance in structure over all the 
forms which w r e have hitherto studied—an advance which is 
especially seen in the constant presence of a permanent 


46 


INVERTEBRATE ANIMALS. 


mouth. The Infusoria may be defined as Protozoa which 
are prodded with a mouth , and generally a rudimentary 
digestive canal. They do not possess the power of emitting 
pseudopodia , but are f urnished with vibratile cilia or con¬ 
tractile filaments. They are mostly microscopic in size , atid 
their bodies usually consist of three distinct layers. They 
are mostly simple free-swimming organisms, but they some¬ 
times form colonies by budding, and are fixed to some solid 
object in their adult condition. As types of these two sec¬ 
tions of the Infusoria , we may take respectively Paramoecium 
and Epistylis. 

Paramoecium (Fig. 10) is a beautiful slipper-shaped little 



Fig. 10.— Ciliated Infusoria. A. Paramoecium , showing the nucleus (ri) and two con¬ 
tractile vesicles (?;); B. Paramoecium bursaria (after Stein), dividing' transversely, 
n Nucleus; n' nucleolus; v Contractile vesicle; C. Paramoecium aurelia (after Ehren- 
berg), dividing longitudinally. 


creature, which may be found commonly in stagnant waters 
or in artificially-prepared infusions. The body is nearly quite 
transparent, and consists of three layers—1. A structureless, 
transparent, external film or pellicle; 2. A central mass of soft 
semi-fluid sarcode; and 3. An intermediate layer of firm and 
consistent sarcode. The external membrane or cuticle is 
richly covered with minute vibrating hairs or cilia, which ap¬ 
pear, however, to be really derived from the middle layer. 
The cuticle is also perforated by the aperture of the mouth, 
which is continued into a short, funnel-shaped gullet. The 
gullet, however, is not continued into any distinct stomach, 
but opens directly into the soft, semi-fluid sarcode which con¬ 
stitutes the central abdominal cavity. The particles of food 













INFUSORIA. 


47 


on passing through the gullet are directly received into the 
central mass of diffluent sarcode, where they undergo a kind of 
slow circulation or rotation. As in the case of the Amoeba , 
each particle of food generally carries with it a little water, so 
that the appearance is produced of a number of little clear 
spaces in the central sarcode. These are now called vacuoles, 
or food-vacuoles; but they were originally described by Ehren- 
berg, the famous Prussian microscopist, as so many distinct 
stomachs, in consequence of which he named the Infusoria the 
Polygastrica (Gr. polus , many; and gaster, stomach). The 
vibrating cilia which clothe the surface of Paramoecium serve 
partly to drive the animal rapidly through the water, and partly 
to set up currents by means of which food is conveyed to the 
mouth. All the nutrient particles obtained in this way undergo 
the circulation in the central sarcode above spoken of, where 
they are partially or completely digested. The indigestible 
portions of the food appear to be got rid of by a second aper¬ 
ture {anus) placed near the mouth. The only other organs 
possessed by Paramoecium are the so-called nucleus and 
nucleolus, and the contractile vesicle (or vesicles), all of which 
appear to be situated in the cortical layer of the body. The 
nucleus (Fig. 10, n) is a little solid body, composed of an ex¬ 
ternal membrane, with granular contents, and having the 
nucleolus {n') firmly attached to its exterior in the form of a 
little spherical particle. Both appear to be organs of repro¬ 
duction, the nucleus being an ovary, and the nucleolus a 
spermarium. The names, therefore, of nucleus and nucleolus 
are extremely inappropriate, as they lead to confusion with the 
wholly distinct structures which receive these names in an 
ordinary animal or vegetable cell. The contractile vesicle (v) has 
exactly the same structure as in the Amoeba. It is simply a 
little contractile cavity filled w T ith a fluid apparently derived 
frcm the digestion, and contracting and dilating at regular 
intervals. There is usually only a single vesicle present, but 
there may be two or more. 

Reproduction in Paramoecium may be effected by fission— 
that is to say, by a simple splitting of the body of a single in¬ 
dividual into two portions, each of which becomes a fresh 
being. The process of fission may commence at the surface, 
or it may begin at the nucleus. In other cases, two Para- 
moecia come together and adhere closely to one another. The 
nucleus and nucleolus enlarge, and the nucleolus of each is 
transferred to the other, apparently through the mouth. As 
the result of this, numerous germs are produced, which, after 


48 


INVERTEBRATE ANIMALS. 


their liberation from the body of the parent, are developed 
into fresh individuals. 

Epistylis , which is a good example of the fixed Infusoria , 
may be regarded as essentially similar to Paramoecium in its 
anatomical structure. In place, however, of a single free- 
swimming organism, we have now a colony of more or less 
closely related beings, the whole assuming a plant-like form, 
and being rooted to some solid object. The colonies of 
Epistylis may not uncommonly be found adhering to the 
stems of water-plants or to the backs of our common water- 
beetles, and the trained eye readily recognizes them as a 
grayish-white down or nap. On placing a portion of this 
under the microscope, we see a number of little oval cups or 
“ calyces” supported upon a branched stem. Each cup con¬ 
tains a sarcode-body, essentially the same as Paramoecium 
in structure, consisting of granular sarcode, with vacuoles, a 
nucleus, and a contractile vesicle. The end of the cup farthest 
from the stalk terminates in a rounded aperture, through 
which there can be protruded a ciliated disk. On one side 
of this disk is the aperture of the mouth, leading into a kind 
of gullet, which is also furnished with large vibrating cilia. 
This, in turn, opens directly into the soft, granular sarcode 
of the abdominal cavity, which exhibits a constant though 
slow rotation. 



Fig. 11.—Ciliated Infusoria, a Vaginicola; & Stentor MiUleri, the Trumpet Animalcule; 
c Group of Vorticella); d Detached bud of Vorticella. 


A still commoner and equally beautiful example of the 
Stalked Infusoria is the so-called Bell-animalcule ( Vorticella , 
Fig. 11, c), which may be found in any stagnant pool attached 



INFUSORIA. 


49 


to the stems of aquatic plants. The body in Vorticella forms 
a kind of cup or “ calyx ” supported upon a long stalk, which 
is in turn fixed to some solid object. The stem contains a 
contractile fibre in its interior, and the animal can by this 
means push itself out or coil itself up with the utmost rapidity. 
The vibrating filaments or cilia are not scattered over the 
whole surface of the bell-shaped body, but are collected to 
form a kind of fringe or circle round the mouth of the calyx. 
Nearly in the centre of this ring, or on one side, is placed the 
aperture of the mouth, which leads by a short gullet straight 
into the central soft sarcode of the interior of the body. A 
nucleus and contractile vesicle are also present, so that in the 
essential points of its anatomy Vorticella does not differ from 
a free-swimming Infusorian such as Paramoecium. Indeed, a 
transition between the two forms is found in the so-called 
Trumpet animalcule or Stentor (Fig. 11, #), which can detach 
itself and swim about at will, at the same time that it is 
ordinarily fixed by its thinner extremity to some solid object. 
In Vaginicola (Fig. 11, a), again, we have an animalcule 
closely related to Stentor , but having the body protected by a 
horny or membranous sheath. 

All the Infusoria we have been hitherto considering belong to a section 
of the class in which the surface is furnished with more or less numerous 
cilia. There are other forms, however, in which there are no cilia, but the 
body is furnished with a number of radiating filamentous tubes, the extremi¬ 
ties of which form little sucking-disks. Finally, there is another section in 
which the organs of locomotion are in the form of long, contractile filaments, 
termed “ flagella,” which may be combined with cilia, or may be the only 
locomotive organs present. In accordance with these differences, the Infu¬ 
soria are divided into the three orders of the Ciliata , Suctoria , and Flagel- 
lata , of which the ciliated forms are by far the most numerous and most im¬ 
portant. 

Distribution of Infusoria in Space. —As regards the distribution of 
Infusoria in space, there is little to say, except that they are of universal 
occurrence in fresh water over the whole globe, and that they occur also in 
the sea. In fact, the only conditions which appear to be necessary for their 
existence are a certain quantity of water holding organic matter in solution. 
Wherever these conditions are fulfilled. Infusoria are certain to make their 
appearance. The attached forms of Infusoria , however (such as Vorticella , 
Fpistylis, Stentor , and others), do not appear to be ever developed in artifi¬ 
cial infusions, and they are to be sought for on the stems of water-plants, 
and in other similar localities. It seems hardly necessary to remark that, 
as before defined, the occurrence of fossil Inf usoria is not to be looked for, 
as they possess no hard structures which are capable of permanent preser¬ 
vation. It is only to be added in this connection that, if the animalcule 
known as Noctiluca be rightly referred to this class, the Infusoria take a 
very decided share in producing the diffused phosphorescence or luminosity 
of the sea, which is occasionally such a beautiful spectacle even in our own 
climate. 


SUB-KINGDOM II— C(ELENTERATA. 


CHAPTER IV. 

1. Characters of the Sub-Kingdom. 2 . Divisions. 

3. General Characters of the Hydrozoa. 

4. Explanation of Technical Terms. 

In the sub-kingdom Coelenterata are included the sea- 
anemones, corals, sea-jellies, sea-firs, and other allied animals, 
and the whole division may be looked upon as forming the 
most typical section of the animals formerly called by Cuvier 
Padiata. In addition, however, to the above-mentioned ani¬ 
mals, Cuvier included in his Padiata all the members of the 
modern sub-kingdom Protozoa, together with the sea-mats or 
lowest class of the Mollusca , and the sea-urchins, star-fishes, 
wheel-animalcules, internal parasites, and others which are 
now placed in a separate sub-kingdom by themselves (Annu- 
loida). The old Padiata , therefore, was an extremely hetero¬ 
geneous assemblage, and there is no advantage to be derived 
from its employment even in works such as this present. The 
division Coelenterata , or “ hollow-entrailed ” animals (Gr. 
hoilos , hollow; and enter on, intestine), includes all those radi¬ 
ate animals which are more or less closely allied to the sea- 
anemones on the one hand, and to the sea-firs on the other. 
Most of the Coelenterata come under the conveniently loose 
term of “ zoophytes,” or plant-animals, from the external re¬ 
semblance which many of them show to plants. 

The Coelenterata may be defined as animals whose aliment¬ 
ary canal communicates freely with the general cavity of 
the body (“somatic cavity”). The body is essentially com¬ 
posed of two layers or membranes, an outer layer or “ ecto¬ 
derm ,” and an inner layer or “ endoderm .” No circulatory 
organs exist, and in most there are no traces of a nervous 


COELENTERATA. 


51 


syste?n. Peculiar stinging organs, or “ thread-cells” are 
usually if not always present, and in most cases there is a 
radiate or star-like arrangement of the organs, which is 
especially perceptible in the tentacles, which are in most in¬ 
stances placed round the mouth . Distinct reproductive organs 
eteist in all. 

The leading feature which distinguishes the Coelenterata, 
and the one from which the name of the sub-kingdom is de¬ 
rived, is the peculiar arrangement of the digestive system. In 
the Protozoa, as we have seen, a mouth is only very rarely 
present, and in no case is there any definite internal cavity 
bounded by the walls of the body, to which the name of 
“ body-cavity” or “somatic cavity” could be properly applied. 
In most of the higher animals, on the other hand, not only is 
a permanent mouth present, but the walls of the body enclose 
a distinct and permanent chamber or body-cavity. Further, 
in most cases the mouth opens into an alimentary or digesti ve 
tube, which is always distinct from the body-cavity, and never 
opens into it, usually passing through it to open on the sur¬ 
face by another distinct aperture (the anus). In most cases, 
therefore, the alimentary canal is a tube which communicates 
with the outer world by two apertures—a mouth and an 
anus—but which simply passes through the body-cavity with¬ 
out in any way communicatings with it. In the Coelenterata 
(Fig. 12) the condition of partsre intermediate in its arrange- 



Fig. 12.—Diagrammatic vertical section of a Sea-anemone {Actinia), a Stomach; b Mesen¬ 
tery ; c Convoluted cord or 1 craspedum; ” d Tentacle. The dark line indicates the 
“ ectoderm," the fine line and clear space adjacent mark the “endoderm.” 


ment. There is a distinct and permanent mouth, and there 
is a distinct and permanent body-cavity, but the mouth opens 



52 


INVERTEBRATE ANIMALS. 


into, and thus communicates freely with, the body-cavity. In 
some cases the mouth opens straight into the general body- 
cavity, which then serves as a digestive cavity as well (Fig. 
13, a). In other cases there intervenes between the mouth 
and the body-cavity a short alimentary tube, which communi¬ 
cates externally with the outer world through the mouth, and 
opens below by a wide aperture into the general cavity of the 
body. In no case is there a distinct intestinal tube which 
runs through the body-cavity and opens on the surface by a 
mouth at one end and an excretory aperture or anus at the 
other. Another leading character of the Coelenterata is the 
composition of the body out of two fundamental membranes 
(Fig. 12), which are usually of a very simple structure, but 
which may be more or less complicated by the development 
of muscular fibres and other tissues. The outer of these 
layers or membranes is known as the “ ectoderm,” and it 
forms the whole of the outer surface of the body, terminating 
at the margins of the mouth. The inner layer is known as 
the “ endoderm,” and it lines the whole of the interior of the 
body, being prolonged into the tubular tentacles round the 
mouth. Both of these membranes, but especially the endoderm, 
are usually more or less richly furnished with vibrating cilia. 
The peculiar microscopic organs called “ thread-cells,” or “ net¬ 
tle-cells,” which communicate to many of the Coelenterata 
(such as the sea-jellies) their peculiar power of stinging, are 
structures found in the integument of almost all the mem¬ 
bers of this sub-kingdom, and sometimes in internal parts as 
well. They are very beautiful objects of microscopical ex¬ 
amination, and differ very considerably in the details of their 
structure. They are, however, in most respects essentially 
the same as in the common Hydra or fresh-water polype, in 
which the thread-cells (Fig. 13, d) are “oval elastic sacs, con¬ 
taining a long, coiled filament, barbed at its base and serrated 
along its edges. When fully developed the sacs are tensely 
filled with fluid, and the slightest touch is sufficient to cause 
the retroversion of the filament, which then projects beyond 
the sac for a distance, which is not uncommonly equal to many 
times the length of the latter” (Huxley). 

In accordance with the above-mentioned differences in the 
arrangement of the digestive system, the Coelenterata are 
divided into two great classes, termed respectively the Hy- 
drozoa and the Actinozoa. In the Hydrozoa , there is no 
body-cavity distinct from the digestive cavity—or, in other 
words, the body-cavity is the digestive cavity. In the Acti- 


CCELENTERATA. 


53 


nozoa , on the other hand, there is a distinct digestive cavity, 
but this opens directly into the general body-cavity, so that 
the two form distinct but freely-communicating divisions of 
the same chamber. 


Class I.— Hydrozoa. 

The Hydrozoa are defined as Coelenterata in which the 
walls of the digestive sac are not separated from those of the 
general cavity of the body , the two coinciding with one an¬ 
other. The reproductive organs are external , in the form of 
outward processes of the body-wall (Fig. 13, a, b). 

The Hydrozoa are all aquatic in their habits, and, with 
the exception of two genera, all are inhabitants of salt water. 
The class includes both simple and composite organisms, of 
which the most familiar are the sea-firs and their allies (Hy- 
droid zoophytes), the fresh-water polype or Hydra , the sea- 
jellies ( Medusae ), and the Portuguese man-of-war (. Physalia ). 
Owing to the extremely complicated nature of many of the 
Hydrozoa , it appears advisable to preface their description 
by an explanation of some of the more important terms which 
are employed in connection with various members of the 
class. 

General Terminology of the Hydrozoa. 

Individual. —In order to understand fully the meaning 
which is attached to the term “ individual ” in zoological lan¬ 
guage, it is necessary to glance briefly at the general features 
of reproduction as displayed in different sections of the ani¬ 
mal kingdom. Reproduction is the process by means of which 
new individuals are produced and the perpetuation of the 
species insured. This end may be attained in various ways, 
but these all come under the two heads of “ sexual ” and 
“ non-sexual ” reproduction. In sexual reproduction, by which 
alone can fresh beings be produced among the higher ani¬ 
mals, the essential element of the process consists in the 
formation of two distinct structures, a germ-cell or ovum, and 
a sperm-cell or spermatozoid. By the union of these distinct 
reproductive elements fresh beings can be produced. As a 
general rule, the germ-cell is produced by one individual 
(female), and the sperm-cell by another (male); but among 
the lower animals it is not uncommon for the same individual 
to produce both of these elements, in which case the indi¬ 
vidual is said to be “hermaphrodite.” Among the lower 
animals, however, fresh beings may be produced without the 


4 


54 


INVERTEBRATE ANIMALS. 


contact of a sperm-cell and an ovum—that is to say, without 
any genuine act of reproduction. The processes by which this 
can be effected in different animals vary considerably, but they 
are all spoken of as forms of “ non-sexual ” reproduction. The 
only varieties, however, of the process which require considera¬ 
tion, are those in which fresh beings are produced by what 
is called “ gemmation ” or “ fission.” 

Gemmation (Lat. gemma , a bud) consists in the produc¬ 
tion of a bud or buds, usually from the outside, but sometimes 
from the inside, of an animal; which buds become developed 
into more or less completely independent beings. The fresh 
beings thus produced by budding are all known as zooids , and 
are not spoken of as distinct animals for reasons which will be 
immediately evident. When the zooids produced by budding 
remain permanently attached to one another and to the parent 
organism which produced them, the case is said to be one of 
“continuous” gemmation, and the ultimate result of this is 
to produce a colony or composite structure, composed of a 
number of similar and partially independent beings, all pro¬ 
duced by budding, but all remaining in organic connection. 
This is seen very well in the sponges, in the compound Fora- 
minifera , and in a great number of the Hydrozoa. When, on 
the other hand, the zooids produced by budding become finally 
detached from the parent organism, we have a case of what is 
called “ discontinuous ” gemmation. In this case, the detached 
zooids become completely independent beings; and they are 
often wholly unlike the original zooid in structure and in 
habits, so much so that they have in various cases been de¬ 
scribed as altogether distinct animals. Discontinuous gem¬ 
mation is very well seen in many of the Hydrozoa , and in 
them the case is still further complicated by the coexistence 
of discontinuous gemmation with the continuous form of the 
process. Thus, it is not an uncommon thing among the 
Hydrozoa to find a composite organism or colony produced 
from a primordial zobid by continuous gemmation, and hav¬ 
ing at the same time the power of giving rise to detached and 
completely independent beings by a process of discontinuous 
gemmation. 

In what is called “fission” (Lat. findo , I cleave), exactly 
the same results are attained as in gemmation, but in a 
slightly different manner. In gemmation the new beings are 
produced by means of buds thrown out by a primitive zobid. 
In fission the new beings are produced by a cleavage or 
division of a primitive zooid into two or more parts, each of 

0 


CCELENTERATA. 


55 


which becomes finally developed into a new and more or less 
completely independent being. In fission, as in gemmation, 
the new beings or zobids may remain permanently in con¬ 
nection with one another, when the process is a continuous 
one, and a composite organism is produced, as in many corals. 
Or, in other cases, the new zobids produced by fission are de¬ 
tached to lead an independent existence, as in some of the 
Ihjdrozoa , the process thus becoming a discontinuous one. 

We are now able to understand what is meant, in strict 
zoological language, by the term “ individual,” as applied to 
animals. Zoologically speaking, an individual is defined as 
“ equal to the total result of the development of a single 
ovum.” In the higher animals there is no sort of difficulty 
about this, for each ovum gives rise to no more than one 
single animal, vrtiich cannot produce fresh beings in any other 
way than by producing another ovum. In this case, there¬ 
fore, each animal is an individual. In the lower animals, 
however, the being produced by an ovum has often the power 
of giving rise to fresh beings by a process of gemmation or 
fission, and these beings may either remain attached to one 
another so as to form a colony, or may become detached to 
lead independent lives. In either case, the term “individual” 
can only be properly applied to the whole assemblage of be¬ 
ings produced in this way, however much they may differ 
from one another in appearance, structure, or mode of life. 
In these cases, therefore, the individual may be, firstly , a 
single independent being—as, for instance, an Amoeba , or an 
Infusorian such as Paramoecium ; secondly , a colony or com¬ 
posite organism composed of a number of more or less nearly 
similar beings or zooids, produced by budding from a primi¬ 
tive zooid—as, for instance, a sponge, or such an Infusorian 
as Epistylis ; and thirdly , an assemblage of zobids produced 
by budding or fission from a primitive being, but not neces¬ 
sarily remaining connected with one another or exhibiting 
any common features of likeness, as we shall see is the 
case in many of the Ilydrozoa. Lastly, cases may occur in 
which the individual consists partly of similar zobids which 
remain permanently connected with one another, and partly 
of dissimilar zobids which are detached to lead an independent 
life, all alike being the result of the development of a single 
ovum. 

Zooid (Gr. zoon, animal; eidos , form).—The term “ zooid ” 
is indifferently applied to all the more or less completely in¬ 
dependent beings which are produced by budding, or by 

4 


56 


INVERTEBRATE ANIMALS. 


cleavage from a primitive organism. It does not matter, 
therefore, for the purposes of this definition, whether these 
beings remain permanently attached to the original organism, 
or whether they are finally separated to enjoy an independent 
existence. 

Hydrosoma (Gr. hudra , a water-serpent; soma , body).— 
The term “ hydrosoma ” is one which is very conveniently ap¬ 
plied to the entire organism in any Hydrozoon , whether this 
be simple, or whether it be composite and made up of a num¬ 
ber of connected zooids. 

Poly pits. —That portion of any Hydrozoon which is con¬ 
cerned with the process of digestion, or, in other words, the 
“alimentary region,” is termed the “polypite”—the more 
generally current term of “ polype ” being now restricted in 
meaning to the same region in the higher (Joelenterata ( Ac - 
tinozoa). In such of the Hydrozoa as the fresh-water polype 
or Hydra , in which the hydrosoma is simple, the whole or¬ 
ganism is termed a polypite; but the term is more generally 
employed to indicate the nutritive zoQids of any compound 
Hydrozoon . 

Goenosarc. —The term “ coenosarc ” (Gr. Jcoinos , common; 
sarx, flesh) is employed to designate the common trunk or 
flesh by which the separate polypites of any compound Hy¬ 
drozoon are united into a single organic whole. 

Polypary. —The term “ polypary ” or “ polypidom ” is ap¬ 
plied to the horny or chitinous outer covering or envelope 
with which many of the Hydrozoa are furnished. These terms 
have also been not uncommonly employed to designate the 
very similar structures produced by the much more highly or¬ 
ganized sea-mats and their allies ( Polyzoa :), but it is better to 
restrict their use entirely to the Hydrozoa. 


CHAPTER Y. 


Divisions op tiie Hydrozoa. 


The Hydrozoa are divided into four great divisions, each 
of which requires some notice, as presenting points of special 
interest. These divisions or sub-classes are known by the names 
of Hydroida, Siphonophora, Discophora , and Isucernarida. 

SUB-CLASS HYDROIDA. 

This sub-class comprises all the sea-firs and their allies, 
commonly known to naturalists as the “ Hydroid zoophytes,” 
from their resemblance to the fresh-water polype {Hydra), 
which is also a member of this division. The Hydroida are 
defined by the fact that they consist of an alimentary region 
or “ polypit ef which is furnished with a mouth and prehensile 
tentacles at one end, and with an adherent disk at its other 
extremity. In some few cases the hydrosoma consists of but 
one such poly pi te (as in the Hydrida and some of the Co- 
rynida) / but generally the hydrosoma is composed of a 
greater or less number of similar polypites all united by a 
coenosarc or common trunk (as in the majority of the Corynida, 
and in the Sertularida and Campanularida). In the great 
majority of cases, also, the hydrosoma is not unattached, but 
is fixed to some solid object by one extremity. The Hydroid 
zoophytes exhibit three principal types of structure, which 
constitute so many orders. 

Order I. Hydrida. —In the first order we have only the 
well-known fresh-water polypes or Hydros, of which we may 
take the common green Hydra {II. viridis) as the type. This 
singular little creature may be found with a little trouble in 
most of our streams and pools, and it is quite visible to the 
naked eye, though it can only be satisfactorily examined by 


58 


INVERTEBRATE ANIMALS. 


the help of the microscope. When uncontracted, the body of 
the Hydra is in the form of a cylindrical tube (Fig. 13, a, b), 
composed of the two fundamental layers, the ectoderm and 
endoderm, of which the former contains many thread-cells, 
and is likewise furnished with numerous green granules, stated 
to be identical with “ chlorophyll,” or the green coloring- 
matter of plants. At the base of the cylindrical body is a 
kind of disk-shaped sucker, by means of which the animal can 
attach itself at will to any foreign body. Its favorite position 
appears to be that of hanging head-downward, suspended 
from the stem of some water-plant. It is not, however, per¬ 
manently fixed, but it can detach itself and change its place 
at will. At the opposite extremity of the body is placed the 
aperture of the mouth, surrounded by a circle of from five to 
fifteen small tubular filaments, which are termed, the “ tenta- 



Fig. I 3 -— Morphology of Hydrozoa. a Diagrammatic section of Hydra: the dark line is 
the ectoderm, the fine hne and clear space adjacent indicate the endoderm; b Hu dr a 
viridis , showing a single ovum contained in the body-wall near the lower extremity, 
and two conical elevations containing sperm-cells near the bases of the tentacles, 
c Hydra vulgaris, with an undetached bud—enlarged; d Thread-cell of the Hydra 
greatly magnified. J ’ 


cles (Fig. 13, b). Each tentacle consists of a tubular prolon¬ 
gation of both ectoderm^ and endoderm, and encloses a canal 
which opens at its base into the general cavity of the body. 
The ectoderm of the tentacles is richly furnished with thread- 
cells, and they are also well supplied with muscular fibres. 
They exhibit the most extraordinary contractility, being capa¬ 
ble of retraction till they appear as nothing more than so 
many little warts or tubercles, and of being extended to a 



DIVISIONS OF THE HYDROZOA. 


59 


length which is in some species many times longer than the 
body itself. (In Hydra fusca the tentacles can be protruded 
to a length of more than eight inches.) The tentacles are the 
organs by means of which the Hydra obtains its food, con¬ 
sisting chiefly of minute aquatic organisms, such as small 
worms, insects, Crustacea and JRotifera. These are seized 
by the tentacles and gradually drawn into the mouth ; but in 
addition to this merely mechanical action, the tentacles ap¬ 
pear to exercise a benumbing or even fatal influence upon the 
animals grasped by them—this being apparently due to the 
thread-cells with which they are furnished. The mouth in 
the Hydra opens directly into a capacious cylindrical cavity, 
which is excavated along the whole length of the body, and 
which is both the body-cavity and the stomach in one. This 
cavity (Fig. 13, #, V) is filled with water derived from the 
exterior, and also with the nutritive particles derived from 
the food. Indigestible fragments appear to be rejected by 
the mouth, though an anal aperture has been asserted to be 
present. There are no internal organs of any kind. Physio¬ 
logically, therefore, the Hydra presents little advance upon 
the higher Protozoa , such as the Infusoria. There is a per¬ 
manent mouth, surrounded by permanent and special organs 
adapted for the seizure of food. There is also a permanent 
internal cavity for the reception and digestion of the food, 
but this is not shut oflf from the general cavity of the body. 
There is no organ for the propulsion of the nutritive fluid 
through the body, no nervous system or organs of sense, and 
no special respiratory or excretory organs.' Another and 
striking proof of the essentially low position of the Hydra in 
the animal scale is to be found in its extraordinary capacity 
of resisting mutilation, or, in fact, mechanical injury of any 
kind short of absolute annihilation. The briefest illustration 
of this fact is all that can here be given, but with that the 
name of Trembley of Geneva must be associated. This well- 
known observer, in a long series of experiments, most of 
which have been successfully repeated by subsequent nat¬ 
uralists, discovered that the Hydra could be mechanically 
divided with a knife into any number of fragments, with the 
sole result that each and all of these possessed the power 
of developing themselves into fresh and independent polypites. 
Further, the animal could even be turned inside out, with 
a necessary transposition of the ectoderm and endoderm, 
without any apparent inconvenience or interference with its 
health. 


60 


INVERTEBRATE ANIMALS. 


Reproduction in the Hydra is effected non-sexually by 
gemmation, and sexually by the production of ova and sperm- 
cells ; the former process being followed in summer and the 
latter in autumn, few individuals appearing to survive the 
winter. In the first or non-sexual method, the Hydra throws 
out one or more buds, usually from near the fixed extremity 
(Fig. 13, c). These buds at first consist simply of a tubular 
prolongation of the ectoderm and endoderm, enclosing a 
cavity which communicates with the general cavity of the 
body. A new mouth and tentacles are soon developed at the 
free end of this bud, and after a longer or shorter period the 
new Hydra, thus produced, is detached to lead an independent 
life. Each Hydra can produce many such buds during the 
summer season, and the liberated buds can also repeat the 
same process, so that in this way reproduction is rapidly 
carried on. In the second or sexual method of reproduction, 
ova and sperm-cells are produced toward the winter in ex¬ 
ternal processes of the body-wall. The spermatozoa are de¬ 
veloped in little conical elevations, which are produced near 
the bases of the tentacles ; and the ova are formed in much 
larger elevations, of which there is ordinarily but one, placed 
nearer to the fixed extremity of the animal (Fig. 13, b). When 
mature, the ovum is fertilized by the sperm-cells, both being 
set free into the water by the rupture of the body-wall. The 
embryo Hydra is at first covered with vibrating cilia, and 
swdms freely about, until it meets with a suitable locality. 
It then fixes itself by one extremity, the cilia drop off, and 
a mouth and tentacles are developed at the free end of the 
body. 

Order II. Corynida. —In the second order of the Hydroid 
zoophytes, known as the Coryrdda or Tubular Ida, we have a 
number of organisms which in their essential structure are 
closely related to the Hydra , but which differ considerably 
in the nature of the reproductive process. All of them are 
marine, with the single exception of the genus Cordylophora, 
which inhabits fresh water. Some of the members of the 
order are simple, consisting of no more than a single polypite. 
In these cases there is an exceedingly close approach to the 
structure of the common Hydra , but the polypite is per¬ 
manently fixed without the power of voluntarily changing its 
place, while the reproductive process is considerably different. 
In the majority of the Corynida , however, the hydrosoma is 
compound, consisting of a greater or less number of separate 


DIVISIONS OF THE HYDROZOA. 


61 


polypites or zotjids, all connected with one another by a com¬ 
mon flesh or coenosarc, and all forming parts of a plant-like 
rooted colony. In some of the Corynida the polypites are 
naked, but in most cases the coenosarc is protected by a 
horny-looking cliitinous * envelope or “ polypary,” as in 
Tubularia indivisa (Fig. 14)1 In no case, however, is this 
horny covering so prolonged as to 
form little cups in which each poly- 
pite is contained. It always stops 
short at the bases of the polypites, 
and in this way the Corynida can al¬ 
ways be distinguished from their near 
allies, the sea-firs ( Sertularida ). 

As a good example of the Cory- 
nida , the common pipe - coralline 
(Tubularia indivisa) may be taken. 

In this animal (Fig. 14) we have a 
gregarious zoophyte consisting of 
numerous clustered horny tubes, fixed 
by their bases to shells or stones, and 
inhabiting most seas. The tubes are 
usually unbranched, though often con¬ 
siderably interwoven together. Each 
tube is filled with a soft, semi-fluid, 
reddish coenosarc, and gives exit at 
its free extremity to a single poly- 
pite. The polypites are bright red in 
color, and are not retractile within 
their tubes, the horny polypary ex¬ 
tending only to their bases. The 
polypites are somewhat conical in 
shape, the mouth being placed at the 

apex of the cone, and they are furnished w T ith two sets of ten¬ 
tacles. One set consists of numerous short tentacles placed 
directly round the mouth, the other is composed of from 
thirty to forty tentacula of much greater length arising from 
the polypite about its middle or near its base. Near the in¬ 
sertion of these tentacles the generative buds are produced at 
proper seasons. In Eudendrium (the branched pipe-coral¬ 
line) the essential structure is much the same as in Tubularia , 
but the hydrosoma is now truly compound, consisting of a 
number of non-retractile reddish polypites, united by a coeno- 

* Chitine is a substance which is nearly allied to horn, but is distinguished from it by 
the fact that it is not soluble in caustic potash. 

4 






62 


INVERTEBRATE ANIMALS. 


sarc, which is furnished with a horny polypary, the whole 
colony assuming a singularly close resemblance to a plant. In 
Cordylophora —the only fresh-water member of the order—we 
find also a branched composite hydrosoma carrying numerous 
polypites, and having the coenosarc defended by a horny sheath 
(Fig. 15, a , b). In Coryomorpha , finally, we have a type of the 



Fig. 15. —a Fragment of Cordylophora lacustris , slightly enlarged; h Fragment of the 
same, considerably enlarged, showing a polypite and three gonophores in different 
6tages of growth; c Portion of Syncoryne Sarsii , with medusiform zooids budding be¬ 
tween the tentacles. 


Corynida , in which the hydrosoma consists of no more than a 
single polypite, and there is no polypary. It is about four 
inches in length, and is fixed by filamentous roots to the bot¬ 
tom of the sea. It consists of a single whitish potypite, striped 
with pink, and terminating upward in a pear-shaped head, 
furnished with two sets of tentacles, the shortest of which 
form a circlet round the mouth. 

As regards the generative process in the Corynida , it may 
be as well to consider the general phenomena of reproduction 
as carried on by all the Hydroid zoophytes, the general char¬ 
acters of the process being of a most remarkable nature. As 
has been already explained, the individual in the case of the 
compound Hydrozoa consists of an aggregation or colony of 
partially independent beings or zooids, produced by gemma¬ 
tion or fission from a primordial organism. This is the case 
in all composite animals, such as sponges, sea-mats, corals, 
and many others. In many of the compound Hydrozoa , how¬ 
ever, the case becomes still further complicated. In many of 
these organisms, namely, the zooids differ very much from one 
another both in structure and in function. One set of zooids 



DIVISIONS OF THE HYDROZOA. 


63 


is entirely devoted to the duty of providing food for the col¬ 
ony, and in these no reproductive organs are ever developed. 
These nutritive zooids are all like each other in form, and the 
whole assemblage of them has been appropriately termed the 
“trophosome” (Allman), from the Greek trepho, I nourish; 
and soma , body. The colony or trophosome thus formed by 
the nutritive zooids can go on increasing by the production 
of fresh zooids for an almost indefinite period; but in all cases 
there ultimately comes a time when it becomes necessary to 
produce the essential elements of reproduction in order to 
secure the perpetuation of the species. The nutritive zooids, 
as just stated, cannot produce the ova and sperm-cells, being 
destitute of reproductive organs, and the colony is therefore 
compelled to produce a second set of buds, which have the 
power of producing the essential elements of reproduction. 
These buds are collectively called the “ gonosome ” (Gr. 
gonos , offspring; and soma , body). The generative buds 
have the further peculiarity that not only can they produce 
the generative elements, but they are altogether unlike the 
nutritive zooids in appearance. This difference in external 
appearance and in structure is sometimes so great as to lead 
to a most remarkable series of phenomena. In the simplest 
form in which these generative buds or “ gonophores ” appear, 
they have the form of mere protuberances of the ectoderm 
and endoderm (Fig. 16, a ), enclosing a cavity derived from 
the body-cavity. In these buds the generative elements— 
ova and spermatozoa—are developed (Fig. 15, b). In other 
instances, the generative buds have a more complicated struct- 



Fig 16.—Generative buds or gonophores of the JTydrosoa diagrammatically represented. 
a Simple gonophore, consisting merely of a protuberance of the ectoderm and endo¬ 
derm ; c Gonophore which has the structure of a Medusa (medusoid), but is not de¬ 
tached ; d Free medusiform gonophore. 


ure. They consist now (Fig. 16, c) of a bell-shaped disk, 
which is attached by its base to the parent organism, and 
has its cavity turned outward (see also Fig. 15, c). From 



64 


INVERTEBRATE ANIMALS. 


the roof of this disk there is suspended a kind of handle, 
which corresponds to the clapper of the bell, and is termed 
the “manubrium” (Lat. for handle). From the fixed or proxi¬ 
mal extremity of the central process or manubrium proceed 
four canals, which extend to the margin of the bell, where 
they all open into a circular canal surrounding the mouth 
of the bell. This bell-shaped reproductive bud may attain no 
higher development than this, and may remain permanently 
attached to the parent organism from which it is produced. 
In other cases, however, a higher state of development is 
reached (Fig. 16, cl). The generative bud or gonophore be¬ 
comes detached from its parent colony; the manubrium or 
central process develops a mouth at its free extremity; the 
mouth of the bell becomes partially closed by an inward pro¬ 
longation or shelf, called the “ veil; ” and a series of ten¬ 
tacles are developed from its margin. The generative bud, 
thus liberated, leads a wholly independent existence. The 
manubrium, having developed a mouth, assumes the func¬ 
tions of a true polypite, and its cavity acts as a digestive 
sac. The whole organism swims about freely, and has the 
power of assimilating food, and thus of attaining to a com¬ 
paratively gigantic size. This independent existence, how¬ 
ever, only goes on till such time as the elements of reproduc¬ 
tion can be produced. The ova and sperm-cells are developed 
in specialized portions of this generative bud, and then it 
ceases to exist. The ova, however, when fertilized, do not 
develop themselves into the free-swimming bell-shaped or¬ 
ganisms in which they were actually produced, but into the 
plant-like, rooted, and compound zoophyte, from which the 
generative buds were originally given forth. These free- 
swimming bell-shaped reproductive buds or gonophores, as 
we shall see, are identical structurally with the smaller forms 
of the so-called sea-jellies or Medusae ; and it is now known 
that most if not all of these Medusae , though originally de¬ 
scribed as distinct beings, are really nothing more than the 
free generative buds of the fixed Hydrozoa. We have here, 
then, an instance of what has been not quite appropriately 
called “ alternation of generations.” We have a compound 
fixed animal, in many respects comparable to a plant, pro¬ 
ducing a special series of buds which are devoted to the pro¬ 
cess of reproduction. These buds are cast off as independent 
beings to lead an independent life, and they are furnished 
with the necessary organs to preserve their existence till they 
are able to mature the reproductive elements. When once 


DIVISIONS OF THE HYDROZOA. 


65 


able to consummate this, they die; but the young to which 
they give origin are wholly unlike themselves. The young, 
namely, instead of being free-swimming “ medusiform ” beings, 
become developed into the fixed, plant-like colony from which 
the generative buds were originally produced. The term 
“ alternation of generations ” is not an altogether good one, 
and does not quite express the facts of the case. There is 
not any alternation of generations, but there is an alternation 
of generation with gemmation or budding. The only true 
generative act takes place in the reproductive zooid or gono- 
phore, in which the ova and sperm-cells are developed. The 
production of this gonophore from the parent organism (tro- 
phosome) is a process, not of generation, but of gemmation 
or budding. The whole process, therefore, is, properly speak¬ 
ing, not an “ alternation of generations,” but an alternation 
of generation with gemmation. 

To recapitulate, then—the process of reproduction in the 
Hydroid zoophytes is carried on by means of reproductive 
buds or gonophores, which are produced at special seasons, 
and in which the reproductive elements are developed. These 
generative buds differ a good deal in their character, but three 
chief kinds may be distinguished: 1. Simple closed sacs or 
protuberances formed out of both ectoderm and endoderm, 
and having the special elements of generation developed in 
their interior. 2. Bell-shaped buds, attached to the parent 
colony by their bases, and having a central process or manu¬ 
brium, which is furnished with a mouth and central cavity, 
from which there is given ofF a system of canals to ramify in 
the substance of the disk. The reproductive elements are 
developed either in the walls of these canals or between the 
ectoderm and endoderm of the manubrium. From the resem¬ 
blance of these buds in anatomical structure to the so-called 
sea-jellies or Medusae , they are usually spoken of as “ medusi¬ 
form gonophores,” or simply as u medusoids.” In this form, 
however, though highly organized, the buds never become de¬ 
tached from the parent colony. 3. Buds w’hich become de¬ 
veloped into bell-shaped medusiform bodies exactly similar in 
structure to the last, but detached to lead an independent ex¬ 
istence. These free-swimming medusiform gonophores are 
anatomically indistinguishable from ordinary Medusw ; and it 
is now known that most, if not all, of the so-called “ naked¬ 
eyed ” Medusae , are really the detached generative buds of 
other orders of Hydrozoa. The special elements of reproduc¬ 
tion are developed in these detached buds, but the resulting 


60 


INVERTEBRATE ANIMALS. 


embryos are not developed into Medusae , such as produced 
the ova and sperm-cells, but straightway grow up into the 
plant-like, sexless colony, from which the medusiform gono- 
phores were originally budded forth. In these cases, there¬ 
fore, the individual Hydroid consists of a fixed, rooted colony 
or trophosome, producing fresh zooids by a process of budding, 
but incapable of producing the essential elements of reproduc¬ 
tion, together with a free and independent series of generative 
buds, or gonosome, in which the elements of reproduction are 
developed. 

Order III. Sertularida. —In this order of the Hydroida 
we have the most familiar and best known of all our zoophytes 
—namely, the sea-firs and their allies. The horny, plant-like 
polvparies of the Sertularida are familiar to every visitor at 
the sea-side, and by those unacquainted with their true 
nature they are almost universally set down as sea-weeds. 
The Sertularida are very closely allied to the compound forms 
of the Gorynida , resembling them in being rooted, plant¬ 
like colonies, composed of a number of similar polypites or 
zooids, produced by budding from a primitive zooid. As in 
the Tubularians among the Gorynida , the whole coenosarc is 
enveloped in a horny or chitinous envelope or polypary 
(Fig. 17, a ), and this is the structure which is most familiarly 
known to sea-side observers. The Sertularida , however, are 
distinguished from the Gorynida by two points: Firstly, 
none of the Sertularida are simple, but are all compound, con¬ 
sisting of more or less numerous polypites, united by a 
branched coenosarc. Secondly, the polypary of the Sertularida 
differs from that of the Gorynida in not simply reaching to 
the bases of the polypites, but in being prolonged to form a 
number of little cups or “ hydro thecae ” (Fig. 17, a, b) within 
which the polypites are lodged. Each polypite has a cup of 
its own, within which it can entirely withdraw, and from 
which it can protrude its free extremity. 

The polypites of the Sertularida have essentially the same 
structure as in the Gorynida , and each may be compared to a 
little Hydra. Each, namely, consists of a soft, contractile, and 
extensile body, which is furnished at its free extremity with 
a mouth and a circlet of prehensile tentacles, richly furnished 
with thread-cells. The mouth opens into a chamber which 
occupies the whole length of the polypite, and which is to be 
regarded as the combined body-cavity and digestive sac. At 
its lower end this chamber opens by a constricted aperture 


DIVISIONS OF THE IIYDROZOA. 


67 


into a tubular cavity, which is everywhere excavated in the 
substance of the ccenosarc (Fig. 17, b). The nutrient parti¬ 
cles obtained by each polypite thus serve for the support of 




Fig. 17 .—a Sertularia ( Diphnsia) pinnata , natural size; a' Fragment of the same en¬ 
larged, carrying a male capsule (o), and showing the hydrothecae (A); b Fragment of 
Campanularia neglecta (after Hincks), showing the polypites contained in their hy¬ 
drothecae (A), and also the point at which the ccenosarc communicates with the stomach 
of the polypite (c). 


the entire colony, and are distributed throughout the entire 
organism. The nutritive fluid prepared in the interior of each 
polypite gains access through the above-mentioned aperture 
to the cavity of the coenosarc, w T hich, by the combined exer¬ 
tions of the whole assemblage of polypites, thus becomes 
filled with a granular nutritive liquid. This coenosarcal fluid 
is in constant movement, circulating through all parts of the 
colony, and thus maintaining its vitality—the cause of the 
movement being probably due, in part, at any rate, to the 
existence of vibrating cilia. 

The process of reproduction varies somewhat in different 
members of the order. In all alike, however, the ordinary 
polypites are incapable of producing the essential elements 
of reproduction, and for this purpose special generative buds 
have to be developed. In the typical Sertularians the re¬ 
productive buds are developed at certain seasons in great 
numbers, and they constitute what used to be called the 







68 


INVERTEBRATE ANIMALS. 


“ ovarian vesicles ” or “ capsules.” These reproductive buds 
are enclosed in horny cups or receptacles, often of a very 
beautiful shape, and much larger in size than the ordinary 
hydrothecse (Fig. 17, «, a'). Each bud may be compared to a 
polypite destitute of a mouth and tentacles, being composed 
of a protuberance of the ectoderm and endoderm, containing 
a prolongation from the general cavity of the coenosarc. The 
essential elements of reproduction are developed between the 
ectoderm and endoderm of the bud, and the resulting embryo 
is finally liberated as a little oval body covered with cilia, 
with which it swims freely about, until it meets with a suitable 
locality, when it fixes itself, loses its cilia, and by budding 
soon develops another colony. 

In one division of this group—often described as a separate 
order, under the name of Campanularida —some points of 
difference are observable. In the typical Sertularians the 
little cups or hydrothecae for the polypites are placed on the 
sides of the branches, and they are not stalked (Fig. 17, a '), 
while the reproductive elements are pro¬ 
duced in fixed buds. In the Campanu¬ 
larida ;, on the other hand (Fig. 17, b\ 
the hydrothecae are supported upon 
stalks, and are placed at the ends of 
the branches, while the generative buds 
are usually detached to lead an inde¬ 
pendent existence. In these forms the 
reproductive zooids or gonophores start 
as simple buds; but they become grad¬ 
ually developed into free - swimming 
medusoids, such as have been before 
alluded to. Each medusoid consists of 
a little transparent, glassy bell, from the 
under surface of which there is sus¬ 
pended a modified polypite, in the form 
of a manubrium (Fig. 18). The whole 
organism swims gayly through the 
water, propelled by the contractions of 
the bell or disk; and no one would sus¬ 
pect now that it was in any way related 
to the fixed, plant-like zoophyte from 
Fig. is. —Gonophore of one of which it was originally budded off. The 
the Campanularida. central polypite is furnished with a 
mouth at its distal end, and the mouth 
opens into a digestive sac. From the upper end of this stomach 






DIVISIONS OF THE IIYDROZOA. 


69 


proceed four radiating canals which extend to the margins of 
the bell, where they all open into a circular vessel which runs 
round the mouth of the bell. From the circumference of the 
bell hang also a number of delicate extensile filaments or 
tentacles; and the margin is further adorned with a series of 
brightly-colored spots, which are probably rudimentary organs 
of vision and hearing. The mouth of the bell is partially 
closed by a delicate transparent membrane or shelf, the so- 
called “ veil.” Thus constituted, these beautiful little beings 
lead an independent and locomotive existence for a longer or 
shorter period. Ultimately ova and sperm-cells are produced 
in special organs, which are developed in the course of the 
radiating canals of the disk. The resulting embryos are minute 
free-swimming bodies, covered with cilia, which finally fix 
themselves, and develop into the plant-like colonies from which 
the medusoids were derived. 


CHAPTER VL 


SUB-CLASS SIPHONOPHORA, 


The animals included under the name of Siphonop)hora 
are often known as the “ oceanic Hydrozoa,” as they are not 
fixed like the Hydroid zoophytes, but are found swimming at 
the surface of the open ocean, far from land. They are all 
singularly delicate and beautiful organisms, but they require 
little notice here. They are distinguished from the Hydroid 
zoophytes, which we have been just considering, by the fact 
that the hydrosoma consists of numerous polypites, united by 
a common trunk or coenosarc, which is very rarely branched, 
and is never furnished with any hard outer covering or poly¬ 
pary, so that it remains permanently soft and flexible through¬ 
out life. As in the Hydroida , the reproductive organs are in the 
form of special buds, which have the power of developing the 
essential elements of generation, and which are often detached 
as free-swimming medusoids. 

The entire sub-class is divided into two great groups or 
orders, and it will be sufficient to consider shortly a typical 
form of each. In the first order—that of the Galycophoridce — 
the coenosarc is thread-like, cylindrical, unbranched, and highly 
contractile. The cavity of the coenosarc dilates at one end 
into a peculiar ciliated chamber, which is the distinguishing 
character of the order. The name of Galycophoridce (Gr. 
kalux , a cup; and phero , I bear) is, however, derived from 
another circumstance—namely, that one end of the coenosarc 
is always furnished with a series of bell-shaped disks, which 
are known as “ swimming-bells ” or “ nectocalyces.” Each 
nectocalyx consists of a bell-shaped cup (Fig. 19, v , v '), at¬ 
tached by its base to the coenosarc, and having its cavity 
turned outward. In the substance of the disk run at least 
four canals, which communicate with the cavity of the coeno- 






SIPIIOXOPHORA. 


71 


sarc, and proceed to the margin of the bell, where they all 
open into a circular vessel. The mouth of the bell is also 
furnished with a delicate ledge, which runs round its circum¬ 
ference, and is known as the “ veil.” The structure, there¬ 
fore, of the nectocalyces is very similar to that of an ordinary 
medusiform gonophore, the chief difference being the absence 
in the former of the central polypite or 
manubrium. The nectocalyces are highly 
muscular, and have the power of alter¬ 
nately contracting and dilating, thus driv¬ 
ing the whole organism through the water. 

In Diphyes (Fig. 19), which may be taken j 
as the type of the group, there is a long 
thread-like trunk or “ coenosarc ” (c) which 
bears at intervals minute polypites, each 
of which is protected by a delicate glassy 
overlapping plate, termed a “ bract.” At 
one extremity of the coenosarc are two 
large mitre - shaped swimming - bells or 
nectocalyces (v, v'), by the contractions 
of which the entire organism is driven 
through the water. The coenosarc with 
its polypites can be withdrawn, when 
necessary, into a kind of chamber be¬ 
tween the two swimming - bells; but 
when unretracted the organism often 
attains a length of several inches. Its 
name is derived from the fact that the 
two nectocalyces can be separated from 
the coenosarc by the least touch, and it 
was for this reason originally supposed 

to Consist of tWO distinct animals loosely culata, one of the Caiyco- 
attached to one another. The tentacles ^^s^Siming-beiteTo 
are comparatively speaking of great length, Coenosarc, carrying the 

, ^ ~ -it -.i ij. it t_ polypites, each with its 

and are furnished with lateral branches tentacle and protected by 

containing numerous thread-cells. The a bract, 
mouths of the. polypites are not pro¬ 
vided with a circlet of tentacles, but each has a single long 
tentacle arising from near its base. The reproductive organs 
of the Oalycoph or idee are in the form of medusiform gono- 
phores, which are budded from the stalks of the polypites, 
and which are mostly detached to lead an independent ex¬ 
istence. 

The second order of the oceanic Hydrozoa is that of the 



72 


INVERTEBRATE ANIMALS. 


Physophoridce (Gr. physa, a bladder; and phero , I carry), of 
which the most familiar, though not the most typical, example 
is the Portuguese man-of-war, Physalia utriculus (Fig. 20, a). 
The Physophoridce are distinguished from the organisms 
which we have been just considering by the fact that one 
extremity of the coenosarc is developed into a structure which 
is known as the “ float ” or “ pneumatophore ” (Gr. pneuma , 
air; and pliero , I carry). The float contains a larger or 
smaller sac, composed of some elastic, horny substance, proba¬ 
bly chitine, often communicating with the exterior by one or 
more apertures, and always more or less completely filled with 
air. This sac is enclosed in a reflection of the ectoderm and 
endoderm, so that it is really outside the cavity of the coeno¬ 
sarc. The function of the float is no doubt that of enabling 
the organism to maintain its position at the surface of the 
sea. As in the Calycophoridce , the coenosarc is always per¬ 
fectly flexible, contractile, and soft, and is never furnished 
with any chitinous covering or polypary. There may or may 
not be swimming-bells, and the tentacles are very complicated 
in structure, and often attain a length of many inches. The 
polypites present no special points of interest, but are often 
furnished with the protective plates, which have been already 
spoken of as “ bracts.” 

As a good example of the Physophoridce , the Portuguese 
man-of-war may be taken (Fig. 20, a). It is composed of a 
large, spindle-shaped float, often of several inches in length, 
upon the under surface of which are arranged a number of 
polypites, together with highly-contractile tentacles of great 
length, and reproductive organs. The tentacles are richly 
furnished with thread-cells ; and it has the power of stinging 
very severely. Physalia is commonly found floating at the 
surface of tropical and sub-tropical seas, and fleets of it are 
occasionally driven upon temperate shores. 

Another very beautiful member of the Physophoridce is 
the Velella vulgaris , which occurs abundantly in many seas. 
It is about two inches in length by one and a half in height. 
One end of the coenosarc is greatly expanded and flattened out 
into an oval disk, which carries a vertical triangular crest, 
running obliquely across its upper surface (Fig. 20, b). The 
whole organism is semi-transparent and of a beautiful bluish 
color, and it floats at the surface of the sea with the vertical 
crest exposed to the influence of the wind, and thus officiating 
as a sail. From the under surface of the disk are suspended 
the various appendages of the organism, consisting of a single 


sinioNoriioRA. 


73 


large central polypite, a number of processes, like polypites 
in shape, and carrying medusiform gonophores; and lastly, a 
single series of tentacles which arise from the coenosarc quite 
independently of the polypites. 



Fig. 20.—a Portuguese man-of-war (after Huxley); b Velella vulgaris (after OosTe) 





CHAPTER VII. 


SUB-CLASS DISCOPHORA. 


The group of Hydrozoa here spoken of as Discophora or 
3Iedusidae comprises most of the familiar organisms known to 
visitors at the sea-side as sea-jellies, jelly-fishes, or sea-nettles; 
this last name being derived from the power possessed by 
some of them of stinging pretty severely in virtue of the pos¬ 
session of numerous thread-cells. Under the name, however, 
of sea-jellies are included a number of large organisms, ex¬ 
tremely common at certain seasons in our seas, but now 
known to be properly referable to another group of the Hy¬ 
drozoa (viz., Lucernarida). It is these large forms which 
alone possess any power of stinging man, and to these the 
term of “ sea-nettles ” ought properly to be restricted. They 
are better known under the name of “ hidden-eyed ” 3Iedusce y 
applied to them by the late Edward Forbes. Under the 
present group of the Discophora are included only" a number 
of small jelly-fishes, found in great abundance at certain 
times, floating in the open sea, but nevertheless very little 
known to the general public in consequence of their very 
minute size. These delicate and diminutive organisms were 
originally described by Edward Forbes, for reasons to be 
immediately stated, as the “naked-eyed” 3Iedusae. It is now 
known, however, that most of these naked-eyed Medusae are 
in reality nothing more than the free-swimming generative 
buds, or medusiform gonopliores, produced by budding from 
so many of the other Hydrozoa , and then detached, as we 
have formerly seen, to lead an independent existence. That 
this is their true nature, is shown by the fact that the eggs 
which they produce develop themselves, not into fresh Me-_ 
dusce , but into various other forms of Hydrozoa , which are 
fixed or oceanic. Under these circumstances, therefore, the 



DISCOPHORA. 


15 


naked-eyed Medusae which can be shown to be of this nature, 
cannot, of course, be regarded as distinct animals at all. Still, 
there remains a considerable group of naked-eyed Medusae to 
which this explanation has not hitherto been shown to apply. 
In most of the members of this group the course of develop¬ 
ment is quite unknown, and therefore their true nature is a 
matter of doubt. Two families, however, of this group are 
stated to produce eggs which develop directly into Medusae , 
such as those which gave origin to the eggs; and, if this ob¬ 
servation is confirmed, these, at any rate, must be regarded 
as true Discophora. In the mean while, therefore, it is best 
to regard the group of the Discophora or Medusidae as of a 
questionable nature, and as including forms which may ulti¬ 
mately be shown to be nothing more than the detached zoOids 
of other Hydrozoa. Under these circumstances it will not be 
requisite to do more than very briefly to describe the anatomical 
structure of a typical Medusid; and this is the less necessary, 
since it will be seen at once that the structure is in all essential 
respects identical with what has been already described in 
speaking of the free medusiform gonophores of the Hydroid 
zoophytes. 

In all the naked-eyed Medusae , of which Modeeria (Fig. 21) 



Fig. 21.—Naked-eved Medusae, a Sarsia gemmifera; & Modeeria formosa ; c Polyxe - 
nia Alderi (after Gosse). 




76 


INVERTEBRATE ANIMALS. 


may be taken as a good example, the general structure is briefly 
as follows: The hydrosoma is perfectly free and is oceanic, 
being found swimming near the surface in the open ocean. 
The body is composed of a thick, transparent, gelatinous disk 
or swimming-bell (the nectocalyx), by the pulsations of which 
the animal is driven through the water. From the under 
surface or roof of this bell-shaped disk is suspended a single 
polypite (the manubrium), which bears to the disk the same 
relative position as the clapper does to an ordinary hand¬ 
bell. The distal end of the central polypite is furnished with 
a mouth, the lips of which are often prolonged into four 
longer or shorter lobes or processes. The mouth opens into a 
digestive sac, occupying the axis of the polypite; and from 
the upper end of this proceed four radiating canals, which 
run in the substance of the disk to its margin, where they are 
united by a single circular vessel, the whole system con¬ 
stituting the so-called “ gastro-vascular ” canals. The margin 
of the bell is narrowed by a kind of shelf, which runs round 
the whole circumference, leaving a central aperture, and which 
is known as the “veil.” From the margin of the disk hang 
more or less numerous tentacles, which are hollow processes 
of the ectoderm and endoderm, and which communicate with 
the circular vessel of the canal-system. Also round the cir¬ 
cumference of the swimming-bell are disposed certain “ margi¬ 
nal bodies,” which are doubtless organs of sense. Some of 
these marginal bodies consist of little rounded sacs or “ vesi¬ 
cles,” filled with a transparent fluid, and containing mineral 
particles, apparently of carbonate of lime. These are probably 
rudimentary organs of hearing. Others of the marginal bodies 
are in the form of little masses of coloring-matter or pigment, 
often of a strikingly bright color, enclosed in distinct cavities. 
These are known as the “pigment-spots” or “eye-specks,” 
and they are believed to be rudimentary organs of vision. 
They are placed in a conspicuous and unprotected position on 
the margin of the disk, and hence these organisms were termed 
“ naked-eyed ” Medusae by Edward Forbes. The reproductive 
organs are mostly developed in the course of the radiating 
gastro-vascular canals, but are sometimes situated in the walls 
of the central polypite. The above is the essential structure 
of any of the ordinary naked-eyed Medusae ; and it is hardly 
necessary to remark that it is exactly similar to what has 
been formerly described as distinguishing the undoubted free- 
swimming reproductive buds of the fixed Hydrozoa . The 
probabilities, therefore, as before said, are in favor of the belief 


DISCOPIIORA. 77 

that the entire group of the Discophora will have to be ulti¬ 
mately done away with. 

The naked-eyed Medusae are all exceedingly elegant and 
attractive, when examined in a living condition, resembling 
little bells of the most transparent glass, adorned here and 
there with the most brilliant colors. They occur, in their 
proper localities and at proper seasons, in enormous numbers, 
and they constitute one of the staple articles of diet to the 
Greenland whale. They are mostly phosphorescent, or capa¬ 
ble of giving out light at night, and they appear to be one of 
the principal sources of the luminosity of the sea. It does not 
seem, however, that they phosphoresce unless disturbed or 
irritated in some way. 


CHAPTER VIII. 


SUB-CLASSES LUCERNARIDA AND GRAPT0LITIDJ3. 


The last remaining group of the living Hydrozoa is that 
of the Lucernarida (Lat. lucerna, a lamp), under which name 
are included a considerable number of forms, differing from 
one another to a great extent in exter¬ 
nal appearance. It will be sufficient 
here to describe one or two typical 
forms. 

One group of the Lucernarida is 
represented by Lucernaria itself (Fig. 
22), which occurs not uncommonly in 
temperate seas. In Lucernaria we have 
a cup-shaped body, of a more or less 
gelatinous consistence, usually found 
attached by its smaller extremity to 
sea-weeds, this end of the body being 
developed into a small sucker. Like 
the Hydra , however, Lucernaria is not 
fixed, but can detach itself at will, and 
can even swim freely by means of the 
alternate contraction and expansion of 
the cup-shaped body (or “ umbrella,” 
as it is termed). Round the margin of 
the cup are tufts of short tentacular 
processes, and in its centre is fixed a 
single polypite, furnished with a four- 
lobed mouth. The essential elements 
of reproduction are developed within 
the body of Lucernaria itself, and it 
does not give off any generative buds, 
as so commonly occurs in other forms. 



Fig. 22. —Two specimens of Lu¬ 
cernaria auricula attached 
to a piece of sea-weed (after 
Johnston). 


LU CERN ARID A AND GRAITOLITIDyE. 


79 


Another type of the JLucernarida is represented by the 
organisms formerly termed “ hidden - eyed ” Medusae , and 
familiarly known as sea-nettles or sea-blubbers. Every sea¬ 
side visitor is familiar with the great circular disks of jelly 
which are left upon the sands by the retreating tide during 
the summer months; and many must have noticed on a calm 
day the large, transparent disks of these same creatures slowly 
flapping their way through the water. Not a few, too, must 
have learned by painful experience that some of these singular 
organisms have the power of stinging most severely, if in¬ 
cautiously handled. The forms included under the old name 
of “ covered-eyed ” Medusae differ considerably from one an¬ 
other in their nature, and even in their structure, though they 
all present, in spite of their much greater size, a decided re¬ 
semblance to the naked-eyed Medusae already described. Some 
of the covered-eyed Medusae produce eggs which are developed 
into organisms resembling themselves; but most of them are 
now known to be nothing more than the free-swimming re¬ 
productive buds of minute rooted Hydrozoa. It will be suf¬ 
ficient here to describe shortly the life-history of one of the 
more remarkable forms of this section. 

If we commence with the young form of one of these sin- 



Fig. 23.—Development of Lucernarida ( Chri/saora ). a Ciliated embryo; b Hydra-tuba; 
c Hydra-tuba beginning to divide by transverse cleavage; d The cleavage still farther 
advanced; e A form in which the cleavage has proceeded still further, and a fresh circle 
of tentacles has been produced near the base; / Free-swimming, generative zooid, pro¬ 
duced by fission from the Hydra-tuba. 


gular animals, we find that the egg gives origin to a little 
microscopic ciliated body, which swims about freely by means 
of the cilia with which its surface is covered (Fig. 23, a). 





80 


INVERTEBRATE ANIMALS. 


This little body, on finding a suitable locality, fixes itself by 
one end, and develops a mouth and tentacles at the other, 
when it is known as a “ Hydra-tuba ” (Fig. 23, b), from its 
resemblance in shape to the fresh-water polype or Hydra. 
The Hydra-tuba is only about half an inch in height, and it 
possesses the power of forming large colonies by gemmation, 
while it is incapable of developing the essential elements of 
reproduction. Under certain circumstances, however, repro¬ 
ductive zooids are produced by the following singular process: 
The Hydra-tuba becomes elongated, and exhibits a number 
of transverse grooves (Fig. 23, c). These grooves go on get¬ 
ting deeper and deeper, and become lobed at their margins, 
till the whole organism assumes the aspect of a pile of saucers 
placed one above the other (Fig. 23, d). The tentacles now 
disappear, and a fresh circle is formed close to the base of the 
Hydra-tuba (Fig. 23, e), Finally, all the saucer-like segments 
above the new circle of tentacles drop off one by one, and pre¬ 
sent themselves in the form of independent, free-swimming 
Medusae (Fig. 23,/). These reproductive zooids or Medusae 
eat voraciously, and increase rapidly in size, becoming not 
only comparatively, but often actually, gigantic. Thus, in 
one case the reproductive zooid has been known to attain a 
size of seven feet across, with tentacles fifty feet in length, 
though the fixed organism from which it was produced, was 
no more than half an inch in height. These gigantic repro¬ 
ductive bodies live an independent life until they are able to 
produce ova and sperm-cells, when they die. The fertilized 
egg, however, develops itself, not into the monstrous organism 
by which it was produced, but into the little fixed sexless 
Hydra-tuba, from which the generative bud was detached. We 
have, then, here another instance of the so-called “ alterna¬ 
tion of generations.” 

It is now known, then, that most of the great sea-blubbers 
which abound around our coasts in summer are really the 
detached reproductive buds of minute fixed Hydrozoa ; and it 
may be as well to mention the leading features in their struct¬ 
ure, and the points by which they may be distinguished from 
the smaller or naked-eyed Medusae , to w T hich they have a de¬ 
cided superficial likeness. In the commonest forms of these 
zooids (such as the familiar sea-blubbers, Aurelia and Cyanea), 
the body consists of a great bell-shaped gelatinous disk or 
“ umbrella,” from the roof of which is suspended a single 
polypite, the lips of which are extended into lobed processes, 
often extending far below the margin of the disk (Fig. 24). 


LUCERNARIDA AND GRAPTOLITID.E. 81 

The digestive cavity of the polypite gives out from its upper 
extremity a series of radiating gastro-vascular canals, which 
proceed toward the margin of the umbrella. These radiating 
canals are never less than eight in number, and on their way 
to the margin of the disk they break up into a great number 
of smaller vessels, which unite with one another to form a 
complicated net-work. At the margin of the bell they all 



Fig. 24. —Generative zooid of one of the Lucemarida (Chrysaora hysoscclla). (After 

Gosse.) 


open into a circular vessel, which in turn sends processes into 
a series of marginal tentacles, which are often of extraordinary 
length. Besides the,tentacles, the margin of the umbrella is 
provided with a number of marginal bodies, each of w T hich 
consists of a little collection of pigment or “ eye-speck,” and a 
little sac tilled w T ith fluid and containing mineral particles. 
Each of these marginal bodies is covered and concealed from 
view by a kind of hood derived from the ectoderm. Hence 
the name of “hidden-eyed” Medusae applied to these forms, 
in contradistinction to the “ naked-eyed ” Medusae, in which 
the eye-specks are exposed to view. The reproductive organs 
are usually of some bright color, and “form a conspicuous 
cross shining through the thickness of the disk.” 



82 


INVERTEBRATE ANIMALS. 


From the above description it will be evident that there is 
considerable resemblance between the so-called “ hidden-eyed ” 
Medusae, or the reproductive zobids of many of the Lucernarida, 
and the medusiform gonophores of so many of the Hydrozoa, 
as well as the true Discophora or naked-eyed Medusae . The 
differences,however, between them are these: The swimming- 
disk of the naked-eyed Medusae and of any medusiform gono- 
phore is furnished at its mouth with an internal shelf or veil; 
the radiating gastro-vascular canals are very rarely more 
than four in number, and, should they subdivide (as in rare 
cases they do), they do not form an intricate net-work; lastly, 
the marginal bodies are simply placed in an uncovered 
situation on the margin of the disk. In the reproductive 
zooids of the Lucernarida or hidden-eyed Medusae, on the 
other hand, the swimming-disk or umbrella is destitute of 
any marginal shelf or veil; the radiating gastro-vascular 
canals are never less than eight in number, and they split up 
into numerous branches, which unite to form an intricate net¬ 
work ; lastly, the marginal bodies are concealed from view by 
a kind of hood. 

There still remains another family of the Lucernarida (viz., 
Lhizostomidae) in which the reproductive process is carried on 
in the same way as in the forms we have just described, but 
the structure of the reproductive zooids is somewhat different. 
In these, as in Rhizostoma, the generative zoOid is much 
like those just mentioned ; but the umbrella is destitute of 
marginal tentacles; and, in place of a single central polypite, 
there hangs from the under surface of the umbrella a com¬ 
plex tree-like mass, the branches of which end in, and are 
covered by, small polypites and club-shaped tentacles. The 
umbrella itself does not exhibit any difference as compared 
with those already described, but the ova are produced in 
a genital cavity which is placed on the under surface of the 
umbrella. 

Sub-class Graptolitid^:. —Before leaving the Hydrozoa , it will be as well 
to notice very briefly a group of extinct organisms which certainly belong to 
this class, and which probably find their nearest allies in the Sertularians. 
The Graptolitidce are without a single living representative, and their anti¬ 
quity is, indeed, very high, since it is doubtful if they ever pass above the 
group of rocks known to geologists as the Silurian formation. The most 
typical forms of the group agree with the living Sertularians in having a 
horny polypary, and in having the polypites protected by little horny cups 
or hydrothec®, all springing from a common flesh or coenosarc. The typical 
Graptolites, however, differ from all known Sertularians in the fact that the 
bydrosoma was not fixed to any solid object, but was permanently free. 



LUCERNARIDA AND GRAPTOLITHLE. 


83 


Most of them, also, exhibit a very anomalous and remarkable structure, 
termed the “ solid axis.” This is a peculiar fibrous rod, which no doubt 
served to strengthen the polypary, and which is often prolonged beyond one 
or both ends of the polypary in a naked state. There is also good evidence 
that the reproductive process in the Graptolites was carried on in a manner 
somewhat similar to what is seen in the living Sertularians—namely, by 
means of reproductive buds enclosed in horny capsules. Graptolites most 
usually present themselves as beautiful silvery impressions, covering the sur¬ 
face of the black shales of various parts of the Silurian system. 


CHAPTER IX. 


Actinozoa. 

The second great class of the Coelenterata is that of the 
Actinozoa , comprising the sea-anemones and their allies, the 
corals, the sea-pens, the sea-shrubs, and various other organ¬ 
isms. They are all defined as Coelenterate animals in which 
there is a distinct digestive sac which opens below into the 
general cavity of the body , but is nevertheless separated from 
the body-walls by an intervening space , which is divided into 
a number of vertical compartments by a series of partitions 
or “ mesenteries ,” to the faces of which the reproductive organs 
are attached. The Actinozoa (Fig. 12), therefore, differ fun¬ 
damentally from the Hydrozoa in this, that whereas in the 
latter the digestive cavity is identical with the body-cavity, 
in the former there is a distinct digestive sac, which opens 
truly into the body-cavity, but is nevertheless separated from 
it by an intervening space. The result of this is, that while 
the body of a Hydrozoon exhibits on transverse section a 
single tube only, formed by the walls of the combined diges¬ 
tive and somatic cavity, the body of an Actinozgon exhibits 
two concentric tubes, one formed by the digestive sac and the 
other by the general walls of the body (Fig. 25, A). Further, 
in the Actinozoa the reproductive organs are always internal, 
and are never in the form of external processes of the body- 
wall as in the Hydrozoa. 

In their minute structure the tissues in the Actinozoa dif¬ 
fer little from those of the Hydrozoa. The body is essen¬ 
tially composed of two fundamental layers—an ectoderm and 
endoderm; but there are often well-developed layers of mus¬ 
cular fibres, somewhat obscuring this simplicity of structure. 
Thread-cells are most commonly present in abundance. Cilia 
are very generally developed, especially in the endoderm lining 



ACTINOZOA. 


85 


the body-cavity, where they serve to maintain a circulation of 
the contained fluids. The only digestive apparatus consists 
of a tubular or sac-like stomach, which opens interiorly 
directly into the body-cavity (Fig. 12, a), and communicates 



Fig. 25.—A. Transverse section of an Actinozoon,. a Digestive sac; 5 Outer-wall of the 
body or ectoderm; b' Endoderm; m Mesenteries, connecting the stomach with the 
body-walls, and dividing the space between the two into a number of vertical chambers. 
B. Transverse section of the body of a Ilydrozoon, showing the single tube formed by 
the walls of the body. 


with the outer world through the mouth. A nervous system 
has not been shown to exist in any of the Actinozoa except 
the Ctenophora, and in none are there any traces of a circula¬ 
tory system. Distinct reproductive organs are always present, 
and true sexual reproduction occurs in all the members of the 
class. In a great many forms, however, of the Actinozoa we 
have composite organisms or colonies, produced by a process 
of “ continuous ” gemmation or fission, the zooids thus origi¬ 
nated remaining attached to one another. In these cases— 
as in most of the corals—the separate beings or zoOids thus 
produced are termed “ polypes,” the term “ polypite ” being 
restricted to the Ilydrozoa. In the simple Actinozoa , how¬ 
ever, such as the sea-anemones, the term “ polype ” is applied 
to the entire organism, as consisting of no more than a single 
alimentary region. It follows from this, that the entire body 
of any Actinozoon may be composed of a single polype, or 
of several such produced by budding or cleavage, and united 
to one another by a common connecting structure or coenosarc. 
Most of the Actinozoa are permanently fixed, like the corals; 
some, like the sea-anemones, possess a limited amount of 
locomotive power; and one order, the Ctenophora , is com¬ 
posed of highly-active free-swimming organisms. Some of 
them are unprovided with hard structures or supports of any 
kind, as the sea-anemones and Ctenophora ; but a great many 



86 


INVERTEBRATE ANIMALS. 


secrete a calcareous or horny skeleton or framework which is 
known as the “ coral ” or “ corallum.” 

The Actinozoa are divided into four orders—viz., the Zoan- 
tharia , the Alcyonaria , the Mugosa , and the Gtenophora. 

Order I. Zoantharia (Gr. zoon , animal; anthos , flower). 
—The Zoantharia comprise those Actinozoa in which the 
polypes are furnished with smooth , simple , usually numerous 
tentacles , which, like the mesenteries, are in multiples of 
or six. The Zoantharia are divided into three groups, dis¬ 
tinguished from one another by the presence or absence of a 
coral, and by its structure when present. 

The first of these groups is termed Zoantharia malacoder- 
mata , or “ soft-skinned ” Zoantharia , because the polypes are 
either wholly destitute of a coral, or, if there is one, it consists 
merely of little scattered needles or spicules of carbonate of 
lime. Generally, too, the organism is simple, and consists of 



Fig. 26.—Morphology of Actinidce. a Actinia rosea ; b Arachnactis albida (after Gosse).. 

no more than a single polype. The best known of the mem¬ 
bers of this group are the beautiful sea-anemones or animal- 
flowers (Actinidce), which occur so plentifully on every coast 
(Fig. 26, a). It will be as well to describe the structure of a 
sea-anemone somewhat in detail, as in this way a clear notion 
may be obtained of the general anatomy of the Actinozoa. 
The body of an ordinary sea-anemone (Fig. 26, a) is a truncated 
cone or short cylinder, termed the “ column,” and is of a soft, 
leathery consistence. The two ends of the column are termed 








ACTINOZOA. 


87 


respectively the “ base ” and the “ disk,” the former constitut¬ 
ing a kind of sucker, by means of which the animal can attach 
itself at will, while the mouth is placed in the centre of the 
latter. The mouth is surrounded by a flat space, destitute of 
appendages, and the circumference of the disk is in turn sur¬ 
rounded by numerous simple tubular tentacles, arranged in 
alternating rows. The tentacles consist of both ectoderm and 
endoderm, enclosing a tube which communicates with the 
body-cavity. By the muscular contraction of the walls of the 
column, the fluid contained in the body-chambers can be forced 
into the tentacles, which can be thus protruded a great length, 
while they can also be usually retracted. In some cases the 
tentacles are furnished with perforations at their extremities. 
The mouth (see Fig. 12, a) leads directly into the stomach, 
which is a wide, membranous tube, opening by a wide aperture 
into the body-cavity below, and extending about half-way be¬ 
tween the mouth and the base. The wide space between the 
stomach and body-walls is subdivided into a number of sepa¬ 
rate compartments by radiating vertical plates, which are 
called the “ mesenteries,” and to the faces of which the re¬ 
productive organs are attached, in the form of reddish bands, 
containing either ova or sperm-cells. Below the stomach, 
attached to the free edges of the mesenteries, are a series of 
singularly twisted threads or cords (Fig. 12, c), which are 
filled with thread-cells, and are termed “craspeda.” The 
function of these is not well understood; but it is believed 
that in some cases they can be emitted through apertures, 
which are occasionally found in the walls of the column. The 
sea-anemones are mostly to be found between tide-marks, in 
rock-pools, or on ledges of stone, adhering by means of the 
expanded base. They are not, however, permanently fixed, 
but can change their place at will. In the nearly allied 
Ilyanthus and Arachnactis (Fig. 26, b) the base is tapering, 
and it appears that the animal spends the greater part of its 
existence in an unattached, free condition. The true sea- 
anemones, as already said, are all simple, each consisting of 
a single polype; but there are closely-related forms (such as 
Zoanthus ) in which the organism is compound, consisting of 
numerous polypes united by a creeping, fleshy trunk or coeno- 
sarc. 

The second group of the Zoantharia is termed that of the 
Zoantharia sclerodermata , from the nature of the skeleton or 
coral. In this group are all the so-called “reef-building” 
corals, which are the makers of the well-known “ coral-reefs.” 


88 


INVERTEBRATE ANIMALS. 


The members of this group all possess the power of secreting 
carbonate of lime within their tissues, so as to form a more 
or less continuous skeleton or corallum. From the fact that 
this corallum is secreted by the inner layer of the polypes, 
and is therefore truly within the body, it is said to be “ sclero¬ 
dermic,” in opposition to the kind of coral produced by other 
forms (such as the red coral), where the skeleton is secreted 
by the outer layer of the polypes, and is therefore outside 
them. In this latter case the coral is said to be “ sclerobasic.” 
(For illustrations of these different kinds of corals, see Fig. 
29.) In the typical form of sclerodermic coral, the skeleton is 
in the form of a conical cup, the upper part of which is hol¬ 
low. The lower part is divided into a series of compartments 
by vertical plates, which are called the “ septa,” and which 
correspond to the mesenteries of the living animal. Some¬ 
times the space contained within the walls of the cup or 
“ corallite ” is broken up by horizontal plates called “tabular; ” 
but, when these are present, there are generally no septa. In 
the form of coral just described we have a single corallite, 
produced by one polype, and this simple condition may 
be maintained throughout life. In the great majority of 
cases, however, the polypes bud, so as to form a colony, all 
bound together by a common flesh or coenosarc. When such 
a colony, therefore, produces a sclerodermic coral, in place 
of a single corallite, we have a composite skeleton composed 
of a number of little cups or corallites, each of which was 
produced by one polype, and all of which are united by means 
of a common calcareous basis secreted by the coenosarc (Fig. 
29, a ). 

In accordance with their mode of formation, an ordinary 
compound sclerodermic coral may be distinguished from a 
sclerobasic coral by the fact that it would show a number of 
little cups in which the polypes were contained, whereas these 
cups would be absent in the latter. In accordance, also, with 
the fundamental character of the order Zoantharia , the corals 
of the present group always show septa which are some mul¬ 
tiple of Jive or six. 

When it is understood that compound corals, such as we have been 
speaking of, are produced by the combined efforts of a number of polypes, 
essentially the same in structure as our ordinary sea-anemones, it is readily 
intelligible that under favorable circumstances large masses of coral may be 
produced in this way. When these masses attain such a size as to be of 
geographical importance, they are spoken of as “ coral-reefs,” and the phe¬ 
nomena exhibited by these are of such interest as to demand some notice. 
The coral-Droducing polvpes require for their existence that the average 


ACTINOZOA. 


80 


temperature of the sea shall not be less during winter than 66°; and coral- 
reefs are, therefore, not found in temperate seas. Reefs, however, abound 
in all the seas not far removed from the equator, being found chiefly on the 
east coast of Africa and the shores of Madagascar, in the Red Sea and 
Persian Gulf, throughout the Indian Ocean and the whole of the Pacific 
Archipelago, around the West-Indian Islands, and on the coast of Florida. 
The headquarters, however, of the reef-building corals may be said to be 
around the islands and continents of the Pacific Ocean, where they often 
form masses of coral many hundreds of miles in length. According to 
Darwin, coal-reefs may be divided into three principal forms—viz., Fringing- 
reefs, Barrier-reefs, and Atolls, distinguished by the following charac¬ 
ters : 

1. Frigging-reefs (Fig. 27, 1).—These are reefs, usually of a moderate 
size, which may either surround islands or skirt the shores of continents. 
These shore-reefs are not separated from the land by any very deep channel, 
and the sea on their outward margins is not of any great depth. 

2. Barrier-reefs (Fig. 27, 2). — These, like the preceding, may either 
encircle islands or skirt continents. They are distinguished from fring- 
ing-reefs by the fact that they usually occur at much greater distances 
from the land, that there intervenes a channel of deep water between them 
and the shore, and soundings taken close to their seaward margin indicate 
great depths. 



Fig. 27. — Structure of Coral-reefs. 1. Fringing-reef; 2. Barrier-reef; 3. Atoll; a Sea- 
level; b Coral-reef; c Primitive land ; d Portion of sea within the reef, forming a chan¬ 
nel or lagoon. 


As an example of this class of reefs may be taken the great barrier-reef 
on the northeast coast of Australia, the structure of which is on a gigantic scale. 
This reef runs, with a few trifling interruptions, for a distance of more than 
a thousand miles, with an average breadth of thirty miles, and an area of 



























90 


INVERTEBRATE ANIMALS. 


thirty-three thousand square miles. Its average distance from the shore is 
between twenty and thirty miles, the depth of the inner channel is from ten 
to sixty fathoms, and the sea outside is “profoundly deep” (in some places 
over eighteen hundred feet). 

3. Atolls (Fig. 27, 3).—These are oval or circular reefs of coral enclosing 
a central expanse of water or lagoon. They seldom form complete rings, 
the reef being usually breached by one or more openings. They agree in 
all particulars with those barrier-reefs which surround islands, except that 
there is no central island in the lagoon which they enclose. 

The last group of the Zoantharia comprises composite or¬ 
ganisms in which the coenosarc is supported upon a central 
axis or sclerobasic skeleton. These Zoantharia sclerobasica 
require no notice, except simply to remark that they are dis¬ 
tinguished from other sclerobasic corals (such as the Gor- 
gonidaz) by the fact that each polype possesses tentacles which 
are a multiple of six in number. 

Order II. Alcyonaria. —The second great order of living 
Actinozoa is distinguished by the fact that the polypes are 
furnished with fringed tentacles, and that these, as well as 
the mesenteries and somatic chambers, are always some mul¬ 
tiple of four. With one doubtful exception, all the Al- 
cyonaria are composite, their polypes being connected to¬ 
gether by a coenosarc. The body-cavities of the polypes are 
connected with a system of canals which are excavated in the 
coenosarc, and communicate freely with one another, so that a 
free circulation of nutrient fluids is thus kept up. The struct¬ 
ure of the polypes of the Alcyonaria is, in all essential 
anatomical features, the same as in the sea-anemones, the 
number of the mesenteries and tentacles being the chief dis¬ 
tinction. 

Of the various different organisms included under this order, 
one of the best known is the “ Dead-men’s-fingers,” or Alcyo- 
niurn , which occurs commonly in most seas. It forms spongy- 
looking masses of a yellow or orange color, attached to shells 
and other marine objects. The whole mass is covered with 
little star shaped apertures, through which the delicate pol¬ 
ypes can be protruded and retracted at will. Another well- 
known member of this order—the type of another family—is 
the “sea-rod - ” ( Virgularia mirabilis), which occurs not very 
rarely in shallow seas. Virgularia occurs in the form of a long 
rod-shaped body of a light flesh-color, supported upon a cal¬ 
careous rod, somewhat like a knitting-needle, which is covered 
by the coenosarc. From the coenosarc are given out lateral 


ACTINOZOA. 


91 


processes, each of which bears numer¬ 
ous polypes. Closely allied to Virgu - 
laria is the “Cock’s-comb” Pennatula 
(Fig. 28) ; but in this the lower end 
of the coenosarc is naked and fleshy, 
and the polype-bearing fringes are 
considerably longer, giving the whole 
organism very much the appearance 
of a feather. 

Another family of the Alcyonaria 
is represented by the so-called “ Or¬ 
gan-pipe corals,” of which Tubipora 
musica is a well-known example. In 
this there is a well-developed sclero¬ 
dermic coral consisting of numerous 
cylindrical tubes, which are not di¬ 
vided by vertical partitions (septa), 
but which are connected by strong 
transverse plates. The coral is bright 
red in color, and the polypes are usually 
bright green. 

The best known, however, of the 
Alcyonaria is the family Gorgonidce , 
represented by the sea-shrubs, fan- 
corals, and the red coral of commerce. 

A few of the members of this family 
live in temperate waters, but they attain their maximum in 
point of size and' numbers in the seas of the tropics. In all 
the Gorgonidce the organism consists of a composite structure 
made up of numerous polypes united by a common flesh or 
coenosarc (Fig. 29, b\ the whole supported by a central 
branched axis or coral. The coral varies in composition, be¬ 
ing sometimes calcareous—as in red coral—sometimes horny, 
and sometimes partly horny and partly calcareous, as in Isis 
(Fig. 29). In all cases, however, the corallum differs alto¬ 
gether from the sclerodermic corallum, which has been de¬ 
scribed as so characteristic of the reef-building corals. The 
coral in the present instance is always what is called “ sclero- 
basic ”—that is to say, it always forms an internal axis, covered 
by the coenosarc with the polypes produced therefrom. It is, 
therefore, outside the polypes, and bears to the coenosarc the 
same relation that the trunk of a tree bears to its investing 
bark. This is well shown in Fig. 29, 5, where there is repre¬ 
sented one of these sclerobasic corals in which the corallum 



Fig. 28. —Pennatulidae. The Cock’s- 
comb (Pennatula phospho- 
rea). (After Johnson.) 



92 


INVERTEBKATE ANIMALS. 


consists of alternate horny and calcareous joints. The pol¬ 
ypes of all the Gorgonidce agree, of course, with their order 
in having eight tentacles each, and by this they are distin¬ 
guished from the few Zoantharia in which there is a sclero- 
basic coral. 



Fig. 29. —Sclerodermic and Sclerobasic Corals, a Portion of branch of Dendrophyllia 
nigrescens , a sclerodermic coral (after Dana); b Longitudinal section of Isis hippuris, 
a sclerobasic coral, exhibiting the external bark or coenosarc, with its imbedded polypes, 
supported by the internal axis or skeleton (after Jones). 


The best known of the Gorgonidce is the Corallium rubrwn , 
or “ red coral ” of commerce, which is largely imported from 
the Mediterranean. In this species there is a bright-red, 
finely-grooved, calcareous coral, usually more or less repeatedly 
branched. The coral is invested by a bright-red coenosarc or 
bark, which is studded with numerous little apertures. The 
polypes can be protruded from these openings at will, and are 
milk-white in color, with eight fringed tentacles each. The 
entire coenosarc is excavated into a number of communicating 
canals, with which the cavities of the polypes are connected, 
the whole system being filled with a nutritive fluid known as 
the “milk.” 

Order III. Rugosa (Lat. rugosus , wrinkled).—This order 
merely requires mention, as all its members are extinct, and 
are therefore only known to us by their hard parts or skele- 





ACTINOZOA. 


93 


tons. They agree with the Zoantharia sclerodermata in 
having a well-developed sclerodermic corallum, but differ 
from them in the fact that the septa are always some multiple 
of four • and there are generally transverse plates or tabulae 
combined with the vertical plates or septa. On the other 
hand, they agree with the Alcyonaria in having their parts 
in multiples of four, but differ from them in having a well- 
developed sclerodermic corrallum in which septa are present. 

Order IV. Ctenophora (Gr. Jcteis , a comb; phero , I 
carry).—The fourth and last order of the Actinozoa is that of 
the Ctenophora , comprising a number of free-swimming oceanic 
creatures, very different in appearance from any of the forms 
which we have hitherto been considering. They are all trans¬ 
parent, gelatinous, glassy-looking creatures, which are found 
near the surface in the open ocean, swimming rapidly by means 
of bands of cilia. The cilia are arranged in a series of trans¬ 
verse ridges, which are disposed in longitudinal bands, the 
whole constituting locomotive organs which are known as 
“ ctenophores.” In none are there any traces of a corallum or 
skeleton, and thread-cells are asserted to be universally present. 



Fig. 30.—Ctenophora. Plenrobrachia pileus. 


As the type of the order, we may take one of the commoner 
forms, which is known by the name of Plenrobrachia or Cy- 
dippe (Fig. 30). The body of Pleurobrachia is transparent, 
colorless, gelatinous, and melon-shaped, and exhibits two poles, 
at one of which is placed the mouth. The globe-like body is 


94 


INVERTEBRATE ANIMALS. 


divided into a number of crescentic lobes by eight ciliated 
bands or ctenophores, which proceed from near the mouth to 
near the opposite pole of the body. Besides the cilia there 
are two very long and flexible tentacular processes, which are 
fringed on one side by smaller secondary branches. The ten¬ 
tacles arise each from a kind of sac, one placed on each side 
of the body, and they can be instantaneously and completely 
retracted within these sacs at the will of the animal. 1 he 
mouth of Pleurobrachia opens into a spindle-shaped digestive 
sac or stomach, which in turn opens below into a wider and 
shorter cavity termed the “ funnel; ” from this there proceed 
in the axis of the body two small canals, which open at the 
opposite pole of the body. The funnel communicates with a 
complicated system of canals, which are ciliated internally, 
and are filled with a nutrient fluid. In the angle between the 
two canals which run from the base of the funnel to the sur¬ 
face is a little vesicle or sac, believed to be a rudimentary 
organ of hearing, and placed upon this is a little mass which 
is generally believed to be of a nervous nature. If this is 
correct, this is the first indication which we have hitherto en¬ 
countered of a genuine nervous system. The reproductive 
organs are developed in the walls of the canal-system. 

The only other form of the Ctenophora which deserves 
mention is the “Venus’s girdle” (Cesium Veneris ), which 
agrees in essentials with Pleurobrachia , but is greatly enlon- 
gated in a direction at right angles to the alimentary canal, 
till we have a ribbon-shaped body produced, four or five feet 
in length and two or three inches high. Cestum is not un¬ 
common in the Mediterranean, and has the power of phospho¬ 
rescence, appearing at night as a moving and twisting band 
of flame. 


SUB - KINGB OM III.—ANNUL OIDA. 


CHAPTER X. 

ECHINODERMATA. 

Tiie third primary division of the animal kingdom is known 
by the name of Annuloida , and includes two groups of organ¬ 
isms which are extremely unlike one another in appearance, 
and are termed respectively the Echinodermata and the Sco- 
lecida. In the former we have the sea-urchins, star-fishes, and 
their allies, formerly classed in the old sub-kingdom Radiata; 
in the latter are a number of internal parasites, with some 
minute aquatic creatures, all formerly referred elsewhere. Dif¬ 
ferent as are these two groups in appearance and habits, they 
are nevertheless united by the following peculiarities: * They 
possess a distinct alimentary canal , usually communicating 
with the outer world by two apertures (a mouth and a vent), but 
in any case completely shut offfrom the general cavity of the 
body. In all there is a distinct nervous system ; and in all 
there is a peculiar system of canals termed the “ water-vascu¬ 
lar ” or “ aquiferous ” vessels , which usually communicate 
with the exterior of the body. It should be mentioned that 
many naturalists dissent from this grouping together of the 
Echinodermata and Scolecida into a single sub-kingdom, 
Annuloida. Many other arrangements have been proposed, 
most of which present some special advantages and some dis¬ 
advantages. In the mean while, in the confessedly uncertain 
state of this department of Natural History, it has been thought 
well to adhere to the arrangement proposed by Prof. Huxley, 
an arrangement 'with many obvious drawbacks, and at best but 
provisional. 

* Some of the internal parasites of this sub-kingdom have no alimentary canal at all, 
but this does not affect the value of the above definition. 


96 


INVERTEBRATE ANIMALS. 


Class I.— Echinodermata. 

The members of this class are popularly known as sea- 
urchins, star-fishes, brittle-stars, feather-stars, sea-cucumbers, 
etc., and derive their name of Echinodermata (Gr. echinos , a 
hedgehog; and derma , skin) from the generally prickly nature 
of their integuments. In all, the skin is possessed of the power 
of secreting carbonate of lime, but in very different degrees. 
In the sea-urchins this goes so far that the body becomes en¬ 
closed in an immovable box, composed of numerous calcareous 
plates firmly jointed together. In the star-fishes and their 
allies the skin is rendered prickly by grains, tubercles, or 
spines of calcareous matter, and the body is either destitute 
of regular plates or is only partially enclosed by them. In the 
sea-cucumbers, again, the calcareous matter is mostly only 
present in the form of minute grains scattered in the skin. 
When adult, they all show a more or less distinctly radiate 
structure, which is most conspicuous in the star-shaped star¬ 
fishes and sand-stars, but can be detected in all the members 
of the class. When young, however, they almost always ex¬ 
hibit what is called “ bilateral symmetry ”—that is to say, they 
show similar parts on the two sides of the body. In all Ecliino- 
derms there is a water-vascular system of tubes, which is 
termed the “ambulacral system,” which generally communi¬ 
cates with the exterior, and which in most cases is used in 
locomotion. An alimentary canal is always present, and is 
always completely shut off from the general cavity of the 
body. A vascular or circulatory system is sometimes present. 
There are always distinct organs of reproduction, which are 
almost always placed in different individuals, so that the sexes 
are distinct. The nervous system is in the form of a ring sur¬ 
rounding the gullet and sending branches in a radiating man¬ 
ner to different parts of the body. 

The Echinodermata are divided into seven orders, as fol¬ 
lows : 

1. Echinoidea (Sea-urchins). 

2. Asteroidea (Star-fishes). 

3. Ophiuroidea (Sand-stars and Brittle-stars). 

4. Crinoidea (Feather-stars). 

5. Cystoidea (extinct). 

6. j Blastoidea (extinct). 

7. Holothuroidea (Sea-cucumbers). 

This is by no means a true arrangement of these orders, but 
it is convenient to consider them in this sequence. 


ECHINODERMATA. 


97 


Order I. Echinoidea. —The animals included in this order 
vary from the shape of a sphere or globe to that of a disk, and 
they are all commonly known as “ sea-urchins ” or “ sea-eggs.” 
They are all characterized by the fact that the body is encased 
in a “test” or “shell” (Fig. 31, 2) composed of numerous cal¬ 
careous plates mostly immovably jointed together so as to form 
a kind of box. The intestine is convoluted, and there is a 
distinct vent, or anal aperture. 

The test of a sea-urchin, as just said, consists of many cal¬ 
careous plates accurately fitted together, and united by their 
edges. In all living forms the test is composed of ten zones 
of plates, each zone consisting of a double row. In five of 
these zones (1 a, 2 a) the plates are of large size, and are per- 

u b 



the same, viewed from above: a Interambulacra; & Ambulacra. 3. Genital disk of a 
sea-urchin ( Ilemicidaris ) enlarged: c Ocular plate; d Genital plate; e Anal aperture; 
/Madreporiform tubercle. 4. Spine of the same. (After Forbes.) 


forated by no apertures. These are termed the “ interambu- 
lacral areas.” In the other five zones (1 5, 2 b) the plates are 
of small size, and are perforated by little apertures for the 
emission of delicate locomotive suctorial tubes (the so-called 
“ambularcal tube-feet”). These zones are therefore called 
the “ambulacral areas.” Besides these main rows of plates 
w T hich collectively make up the greater part of the test, there 
are other plates placed in the leathery skin round the mouth 
and vent. The most important of these form a kind of disk, 
which is placed at the summit of the shell. This disk (Fig. 
31,3) is composed of two sets of plates—one called the “geni- 





98 


INVERTEBRATE ANIMALS. 


tal plates,” perforated for the ducts of the reproductive organs; 
the other set smaller, and each carrying a little “ eye,” hence 
their name of “ ocular plates.” One of the genital plates is 
also larger than the others, and carries a spongy mass which 
is called the “ madreporiform tubercle,” and which protects the 
entrance of the water-vascular or ambulacral system. The 
whole of the test is covered with numerous tubercles of dif¬ 
ferent sizes, which carry longer or shorter spines (Fig. 32). 
The spines are jointed to the tubercles by a sort of “ ball-and- 



Fig. 32 .—Cidaris papillata (after Gosse). 


socket ” or “ universal ” joint, and they are completely under 
the control of the animal, so as to be used both in locomotion 
and apparently as defensive weapons. In most common species 
the spines are short, but in many tropical forms they attain a 
very great length. Besides the spines, the outer surface of 
the test is furnished with curious little bodies called “ pedi- 
cellariae,” which were long believed to be parasitic. They 
consist of two or three blades mounted upon a flexible stalk 
and constantly employed in snapping together like the beak 
of a bird. They occur in many other JEchinodermata , and 
their use is obscure. 

Locomotion is effected in the sea-urchins by a curious 
system of contractile tubes which are known as the “ambu¬ 
lacral tubes ” or “ tube-feet,” and which are appendages of 
the water-vascular system. The following is essentially the 
arrangement of the whole aquiferous system. From the 
madreporiform tubercle on the largest of the genital plates 





ECniNODERMATA. 


99 


there proceeds a membranous canal by which the outer water 
is conducted to a central tube, which forms a ring round 
the gullet. The tubercle is spongy, and is perforated with 
little holes, and its function is probably to act as a filter, and 
prevent foreign particles gaining access to the interior. From 
the “ circular canal ” round the gullet proceed five “ radiating 
canals ” which take their course toward the summit of the 
shell, underneath the ambulacral areas. In its course each 
radiating canal gives off numerous short lateral tubes—the 
ambulacral tubes or tube-feet—which gain the exterior of 
the shell by passing through the apertures in the ambulacral 
plates of the shell, and v 7 hich terminate in little sucking- 
disks. The tube-feet can be distended with water by means 
of a series of little muscular bladders-placed at their bases, 
and they can thus be thrust far out beyond the shell, into 
w T hich they can be again withdrawn at the will of the animal. 
However long the spines may be, the animal can protrude 
the tube-feet to a still greater length; and by the combined 
action of the little suckers at their extremities locomotion is 
effected with moderate rapidity, considering the bulk of the 
body. 

The digestive system in the Echinus consists of a mouth 
armed with a curious apparatus of calcareous teeth, which 
opens into a gullet, which in turn conducts to a distinct 
stomach. From the stomach there proceeds a long and con¬ 
voluted intestine, which is attached to the interior of the 
shell by a delicate membrane or “mesentery,” and terminates 
in a distinct vent. The surface of the mesentery, as well as 
that of the lining membrane of the shell, is richly ciliated, and 
thus serves to distribute the fluids of the body-cavity to all 
parts of the body. In this way, also, respiration is subserved, 
though it is probable that the chief agent in this function is 
to be found in certain specialized portions of the ambulacral 
system. The circulatory system consists in its central portion 
of two rings placed round the opposite ends of the alimentary 
canal, and united by an intermediate muscular cavity or heart. 
The nervous system consists of a gangliated cord placed round 
the gullet, and sending five radiating branches along the 
ambulacral areas. The sexes are distinct, but in both the re¬ 
productive organs are in the form of five membranous sacs 
placed in a radiating manner in the interambulacral areas, and 
opening at the genital plates. The embryo of the Echinus is 
at first a little free-swimming ciliated organism, and it passes 
through an extraordinary development, which can only be 


100 


INVERTEBRATE ANIMALS. 


alluded to here. In its later stages it was originally described 
as a distinct animal under the name of “ JPluteus .” In this 
state the larva is a curious, easel-shaped body, with a distinct 
alimentary canal and an internal calcareous skeleton, and ex¬ 
hibiting distinct bilateral symmetry. The remarkable point, 
however, about its further development is, that the young 
Echinus is developed out of only a portion of the Pluteus , and 
the greater part of the latter, including the skeleton, is cast 
away as useless. 

The majority of the sea-urchins are found at moderate 
depths in the sea, especially in the neighborhood of oyster- 
banks. Others spend their existence buried in the sand; and 
one species excavates holes for itself in the solid rock, ap¬ 
parently by some mechanical action. 

Order II. Asteroidea (Gr. aster , star; eidos , form).— 
As the structure of the sea-urchins may be taken as embody¬ 
ing the most important anatomical peculiarities of the Echino- 
dermata , and as this has been described at some length, it will 
not be necessary to do more than briefly indicate the more 
important characteristics of the remaining orders. In the 
present order are included all the true star-fishes, the sand- 
stars and brittle-stars being generally regarded as a distinct 



Fig. 33 .—Cribella oculata (after Forbes). 


group. The body in all the Asteroidea is more or less ob¬ 
viously star-shaped (Fig. 33), consisting of a central disk sur¬ 
rounded by five or more lobes or arms, which radiate from the 





ECIIINODERMATA. 


101 


body, are liollow, and contain prolongations from the stomach. 
The body is not enclosed in an immovable box or test, as in 
the sea-urchins, but the integument is of a leathery nature, 
and is richly furnished with calcareous plates, tubercles, and 
spines. The true star-fishes are distinguished from the nearly 
allied brittle-stars ( Ophiuroidea) by the fact that the arms are 
direct prolongations of the body, that they contain prolonga¬ 
tions of the stomach, and that they are deeply grooved on 
their under surfaces for the radiating vessels of the water- 
vascular system, which are further protected by a sort of in¬ 
ternal skeleton. The upper surface of the body and arms is 
richly furnished with calcareous matter, in the form of prickles, 
tubercles, spines, and pedicellarias, these last being peculiarly- 
modified spines. The upper surface, also, exhibits the madre- 
poriform tubercle in the form of a concentrically-striated disk 
placed at the angle between two of the rays, and also the 
aperture of the anus, when this is present. The mouth is 
placed in the centre of the lower surface, and is not furnished 
with teeth. It leads by a short gullet into a stomach which 
usually terminates on the upper surface by an anal aperture; 
but this is occasionally wanting. From the stomach in all 
the Asteroidea proceeds a series of much-branched membra¬ 
nous sacs, two of which are prolonged into each ray. The 
water-vascular or ambulacral system is in most essential re¬ 
spects identical in structure with that of the sea-urchins, 
making due allowance for the different shape of the body. 
The nervous system consists of a gangliated ring surrounding 
the mouth and sending branches along each of the arms. The 
reproductive organs, like the nervous system, exhibit a radiate 
condition, being arranged in pairs in each ray. 

The star-fishes are found on all shores, but many forms are 
properly inhabitants of deep water. They differ much in the 
general shape of the body. In the common cross-fish ( Uraster 
rubens) the disk is small, and is furnished wfith long, finger-like 
rays, which are properly five in number. In the Cribellce (Fig. 
33) the general shape is much the same. In the sun-stars 
(Solaster) the disk is large and well marked, the rays are from 
twelve to fifteen in number, and they are shorter than the 
diameter of the disk. In the cushion-stars (Goniaster) the 
body is in the form of a five-angled disk, more or less flattened 
on both sides, the rays being only marked out by the ambula¬ 
cral grooves upon the lower surface. 

Order III. Ophiuroidea (Gr. ophis , snake; owm, tail; eir 


102 


INVERTEBRATE ANIMALS. 


dos , form).—In this order we have only the common sand-starS 
( Ophiura ) and brittle-stars ( Ophiocoma ), all closely allied to 
the true star-fishes in external appearance, especially in their 
strikingly radiate form. The body in the Ophiuridce consists 
of a circular central disk covered with small calcareous plates, 
and giving off five long, slender, snake-like arms (Fig. 34, a , b ), 
which may be simple or branched, but which do not contain 
any prolongations from the stomach, nor have their under 
surfaces excavated into grooves for the protrusion of ambu- 
lacral tube-feet. The arms, in fact, are not prolongations or 
lobes derived from the body itself, but are special appendages 
added for purposes of locomotion and prehension. The arms 



are very much longer than the diameter of the disk, and are 
protected by four rows of calcareous plates—one above, one 
below, and one on each side. In the centre of each arm is a 
row of calcareous pieces which form a kind of internal axis 


ECHINODERMATA. 


103 


or skeleton, below which is placed the radiating ambulacral 
vessel. All the internal organs are contained within the disk, 
and none of them pass into the arms except the nerve-cords 
and ambulacral vessels. The mouth is placed in the centre 
of the under surface of the disk, and opens into a globular, 
simple stomach, which is not furnished with an anal aperture, 
all indigestible particles being got rid of through the mouth. 
In various points of their anatomy the Ophiuroidea differ 
considerably from the true star-fishes, to which they are most 
nearly related, but these differences do not require further 
notice. 

The habits of the brittle-stars and sand-stars are various, 
but many of them may be found in rock-pools or under stones 
at low water on most shores. 



Fig. 35 .—Comatida rosacea, a Free adult; 5 Fixed young (after Forbes). 


Order IV. Crinoidea (Gr. Jcrinos , a lily; eidos , form).— 
In this order are comprised Echinodermata , in which the 
body is fixed, during the whole or a portion of the existence 
of the animal, to submarine objects by means of a jointed 
flexible stalk or column. The Crinoidea were formerly very 




104 


INVERTEBRATE ANIMALS. 


numerous, both individually and in types, but they are rep¬ 
resented at the present day by no more than three or four 

living forms, of which one 
only (the feather-star) is at 
all of common occurrence. 
The body in the Crinoids con¬ 
sists of a central disk or cup 
formed of calcareous plates, 
and protecting the body of 
the animal. From the mar¬ 
gins of this cup spring five 
or more arms which are ar¬ 
ranged in a radiating manner, 
so as to form a more or less 
feathery crown. In one of 
our living forms, the animal, 
when full grown, is free; but 
in all other living genera, and 
in the great majority of fossil 
forms, the body was attached 
throughout life to the sea- 
bottom by means of a jointed 
stalk attached to the lower 
surface of the cup (Fig. 36), 
thus somewhat resembling a 
lily. 

The commonest living spe¬ 
cies is the rosy feather-star 
(Oomatula rosacea), which 
occurs not very rarely on 
European coasts (Fig. 35). 
This beautiful animal consists 
of a central body or disk, 
from which proceed five ra¬ 
diating arms, which divide 
almost directly after their 
Fig. 36 . — Rhizocrinus lofotensis, a living Origin into two secondary 

branches, so that ultimately 
Cup; cc Arms. there are produced ten long 

and slender rays. Each arm 
is furnished on both sides with a number of little jointed 
lateral processes or “ pinnae,” so as to assume a feather-like 
appearance, from which its popular name is derived. The 
digestive system is furnished with both a mouth and a vent; 











ECHINODERMATA. 


105 


the water-vascular or ambulacral system appears to take no 
part in locomotion, and the reproductive organs are lodged in 
the lateral processes of the arms. The most remarkable point, 
however, about the Comatula is the manner in which it de¬ 
velops itself. When fully grown (Fig. 35, a) it presents no 
small superficial resemblance to some of the Ophiuroideci. 
When young (Fig. 35, b) the Comatula is so different in ap¬ 
pearance from the adult, that it was originally described as a 
distinct animal. It consists now of a little cup-shaped disk 
with ten radiating arms above, produced by the splitting into 
two of five primary rays, and furnished inferiorly with a little 
flexible column or stalk composed of a number of calcareous 
joints. By this jointed stem the body is at this period of 
life fixed to sea-weeds or other submarine objects. When 
sufficiently mature, however, the body drops off its stalk, and 
then only requires to grow in size to become a fully-developed 
Comatula. 

The stalked condition which we have just seen to consti¬ 
tute a merely temporary stage in the life-history of the Coma¬ 
tula is, on the other hand, the permanent state of parts in 
almost all the “ stone-lilies ” and other fossil Crinoidea, and 
in two or three living forms. Of these recent species, one of 
the most remarkable is one which has been recently discovered 
in the Atlantic and North Seas, and which has been described 
under the name of Rhizocrinus lofotensis. This curious species 
(Fig. 36) consists of a little thread-like, jointed stem support¬ 
ing a calcareous cup, from which proceed 
five branched and jointed arms; and the 
stalked condition is here permanently re¬ 
tained during life. 

Orders V. and VI. Cystoidea and 
Blastoidea. —These orders merely require 
to be mentioned here, as all the forms in¬ 
cluded in them are extinct, and are unrep¬ 
resented at the present day by living spe¬ 
cies. In both, the body is enclosed in a 
kind of box formed by jointed calcareous 
plates (Fig. 37), and it was in most cases 
permanently fixed to the sea-bottom by a 
jointed stalk or column. The arms, which 
form so conspicuous a feature in the true Crinoidea , were 
either absent or very rudimentary. Both orders are most 
closely allied to the Crinoidea , and they constitute probably 





106 


INVERTEBRATE ANIMALS. 


the least highly-developed sections of the whole class of the 
Echinodermata. 

Order VII. Holothuroidea. —In this order are comprised 
the highest of the Echinodermata , all very different in out¬ 
ward appearance from any of the forms we have hitherto con¬ 
sidered. They are commonly known as sea-cucumbers, or tre- 
pangs, but they are mostly rare and inconspicuous animals at 
the best. They are all more or less worm-shaped or snail-like 
in form, and they are either altogether destitute of calcareous 
matter in the skin, or with rare exceptions have only scattered 
grains and spines of this material. As a rule, the skin is 
simply leathery, and is endowed with wonderful contractility 
by means of powerful longitudinal and transverse muscles. 
In consequence of this, they can, in many cases, eject all or 
almost all their internal organs, and can sometimes divide their 
bodies into several parts when injured or alarmed. Loco¬ 
motion is effected by alternate extension or contraction of their 
worm-like bodies, by anchor-shaped spicules of lime contained 
in the skin, or by rows of ambulacral tube-feet, like those of 
the sea-urchins, protruded through the integument. Some¬ 
times the tube-feet are scattered over the whole surface of the 
body, and sometimes they are altogether absent. There is 
always a mouth at one extremity of the body, and a distinct 
vent at the other. The mouth is situated anteriorly, and is 
surrounded by a circlet of feathery tentacles (Fig. 38), which 



Fig. 3S.—Holothuroidea. Thyone papillosa (after Forbes). 


are believed to be modified tube-feet. The water-vascular or 
ambulacral system is sometimes quite rudimentary, but in 
other cases it much resembles that of the sea-urchins, except 
that the madreporiform tubercle is not placed on the outside 
of the body, but hangs down freely in the interior of the body. 
In most of the Holothuroidea there are appended to the ter¬ 
mination of the intestinal canal two much-branched tubes, 



ECHINODERMATA. 


107 


which are filled with sea-water from without, and are believed 
to exercise a respiratory function, hence the name of “ respi¬ 
ratory tree ” often applied to them. 

The ordinary species of Holothurians, as already said, are 
all rare, and are mostly only to be obtained by dredging in 
tolerably deep water. Some of the tropical forms attain a 
large size, and some are largely searched after to be sold in the 
Chinese market, being regarded in that country as a delicacy c 


CHAPTER XL 


Class II.— Scolecida. 

In the second class of the sub-kingdom Annuloida are in¬ 
cluded a number of organisms which are, in many cases, very 
unlike one another in external appearance, but which, never¬ 
theless, agree in one or two structural points of importance. 
The most important of these are the possession of a system 
of water-vascular vessels, the absence of a vascular system, 
and the possession of a nervous system composed of no more 
than one or two nervous masses or ganglia. The points by 
which the Scolecida are distinguished from the Echinodermata 
are, the absence of calcareous matter in the skin, the absence 
of any traces of a radiate arrangement of their parts, especially 
of the nervous system, the constant absence of any blood- 
circulatory apparatus, and the course of their development. 
The Scolecida (Gr. sJcolex , a worm) are often vermiform in 
shape, but many of them exhibit no worm-like characters, 
and one whole order is entirely microscopic. A great many 
of the Scolecida are internal parasites in other animals, and 
these are often collectively spoken of as Entozoa (Gr. entos , 
within; zoon , an animal). These parasitic forms subsist by 
an imbibition of the juices of their host through their 
delicate integument. They have, therefore, no necessity for 
acquiring food for themselves; and we find, in consequence, 
that many of them are wholly destitute of an alimentary 
canal, and that in all the organs of “ relation ” are very rudi¬ 
mentary. The Scolecida are divided into the following seven 
groups or orders : 

1. Tceniada (Tape-worms). 

2. Trematoda (Flukes). 

3. Turbellaria (Ribbon-worms and Planarians). 


SCOLECIDA. 


109 


4. Acanthocephala (Thorn-headed worms). 

5. Gordiacea (Hair-worms). 

6. Nematoda (Round-worms and Thread-worms). 

7. Rotifer a (Wheel-animalcules). 

Order I. T^eniada (Gr. tainia , a ribbon).—In this order 
are comprised the ribbon-shaped Tape-worms (Fig. 39, 5) and 




Fig. 39.—Morphology of Taeniada. 1. Ovum containing the embryo in its leathery case; 
2. A bladder-worm (Cysticercm longicollis ), magnified; 3. Head of the adult Tainia 
solium , enlarged, showing the suckers and crown of hooklets; 4. A single generative 
joint, enlarged to show the branched ovary (o), the generative pore (a), and the water- 
vascular canals ( b ); 5. Fragment of Tcenia solium , showing the generative joints and 
the alternate arrangement of the generative pores. 

the bladder-worms or cystic worms (Fig. 39, 2). These were 
formerly described as distinct groups; but it is now known 
that the latter are merely the young forms of the former. The 
peculiarity which distinguishes the development of the Taeni- 
ada , and which led to the cystic worms being described as 
distinct animals, is that the different stages of growth are 
always found inhabiting different animals or “hosts.” If the 
fully-grown tape-worm is found in one animal, then its young 
form or cystic worm will always be found in another. Many 
animals are infested by tape-worms; but all the leading points 
of interest in the order will be brought out by a consideration 
of the commonest of the three tape-worms to which man is 
subject—namely, the common tape-worm, or Taenia solium. 























110 


INVERTEBRATE ANIMALS. 


The common tape-worm is found inhabiting the intestines of 
man, one only being generally present in the same individual. 
In shape (Fig. 39, 5) it is an extremely elongated, flattened, 
tape-like body, many feet in length, and composed of a num¬ 
ber of flattened joints (Fig. 39, 4) all loosely united to one 
another. At one extremity the joints become much smaller 
and narrower, till ultimately a point is reached where the 
organism is firmly fixed to the mucous membrane of the in¬ 
testine by means of a minute rounded head (Fig. 39, 3). 
The organs by which attachment is effected are, in this spe¬ 
cies, a crown of recurved hooks and four suckers. The head 
is in reality the true animal, and all the long, jointed, tape¬ 
like body which follows this, is really produced by a process 
of budding from the head. The head contains no repro¬ 
ductive organs, and is not furnished with a mouth or diges¬ 
tive organs of any kind, its nutrition being entirely effected 
by imbibition of the nutritive fluids elaborated by its host. A 
nervous system, in the form of one or two ganglia, sending 
filaments backward, is said to be present; but there is some 
doubt on this point. The water-vascular system (Fig. 39, 4) 
consists of two long vessels which run down each side of the 
body and communicate at each articulation by a transverse 
vessel, the whole opening in the last joint into a contractile 
vesicle. Each joint is sexually perfect, or hermaphrodite, 
containing both male and female reproductive organs (Fig. 
39, 4), which open on the surface by a small raised aperture, 
the “generative pore.” Almost the whole of each of the 
mature joints is filled up by a much-branched ovary. As the 
head is the true animal, and the numerous joints are only pro¬ 
duced by budding, it follows that the entire organism is to be 
regarded as a kind of colony, constituted by a single sexless 
zo5id or “ nurse,” and numerous sexual zooids, produced by 
budding from the former. 

The process of development—that is to say, the process 
by which this composite organism, commonly known as the 
tape-worm, is produced—is a very remarkable one, and is 
briefly as follows: Each generative segment or joint, as al¬ 
ready said, is hermaphrodite, and contains innumerable ova. 
These eggs, however, cannot be developed within the body 
of the animal infested by the tape-worm itself, but they are 
compelled to gain access to the body of some different species 
of animal, if development is to proceed. To secure this end, 
the mature joints of the colony break off, and are expelled 
from the alimentary canal of the host. The joints thus ex- 


SCOLECIDA. 


Ill 


pelled die and decompose, and their contained eggs are thus 
set free. Each egg (Fig. 39,1) is covered with a little leathery 
capsule which protects it from injury, and contains a minute 
embryo in its interior. If this microscopically small egg be 
swallowed—as in many ways it easily may be—by another 
warm-blooded animal (in this particular case by the pig), 
then a fresh series of changes ensues. The leathery case of 
the ovum is dissolved in the stomach of the new host, and 
the embryo is set free, when it bores its way through the 
walls of the stomach -by means of little siliceous hooks with 
which it is provided. Having reached a suitable locality, the 
young tape-worm proceeds to surround itself with a kind of 
cyst, and it develops from its hinder end a kind of bladder 
filled with fluid (Fig. 39, 2). It is now a bladder-worm, or 
cystic worm, and as such would formerly have been regarded 
as a distinct animal. In the particular case of the Tcenict 
solium which we are now considering, the cystic worm is 
found imbedded in the muscles of the pig, and it constitutes 
in that animal the disease known as the measles. In this 
cystic stage the young tape-woim may remain for an ap¬ 
parently indefinite period, being quite incapable of develop¬ 
ing eggs, though sometimes fresh bladder-worms may be 
produced by a process of budding. For its further develop¬ 
ment it is necessary that it should now be introduced into 
the alimentary canal of man. If a portion of measly pork be 
eaten with these cystic worms imbedded in. it, then the 
young tape-worm is liberated from its cyst: it fixes itself 
by means of its suckers and hooklets to the mucous mem¬ 
brane of the intestine, and its caudal bladder drops off. It is 
now converted into the head of the adult tape-worm. It 
finally commences to throw out buds from its hinder extremity, 
and in these buds or joints the reproductive elements are pro¬ 
duced, so that ultimately we -get the long, flattened jointed 
colony with which we started. 

This extraordinary series of phenomena is now known to 
occur in other cases, but space will not admit our dwelling 
upon these. Another of the tape-worms of man (the Taenia 
mediocanellata) is developed in the same way from the 
measles of the ox. The tape-worm of the cat is the mature 
form of the bladder-worm of mice, and the tape-worm of the fox 
is derived from the cystic worm of hares and rabbits. Lastly, 
man is not only liable to be infested with the tape-worms 
derived from the cystic worms of other animals, but may be 
attacked by the cystic or immature forms of the tape-w'orms 


112 


INVERTEBRATE ANIMALS. 


of other animals. Thus the disease known as w hydatids ” in 
the human subject is caused by the presence in his tissues of 
the cystic worms which are ultimately developed into the tape¬ 
worm of the dog. 

Order II. Trematoda (Gr. trema , a pore or sucker).— 
The “ suctorial ” worms, or “ flukes,” as the members of this 
order are commonly called, are all internal parasites, inhabit¬ 
ing various situations in different animals, but especially af¬ 
fecting birds and fishes. They are all more or less flattened 
and rounded in shape, and are furnished with one or more 
suckers , by which they adhere. They are distinguished from 
the Tceniada by always possessing an alimentary canal, which 
is often much branched (Fig. 40, 1), is simply hollowed out 



Fig. 40— Trematoda. 1. Distoma liepaticum , the “liver-fluke;’ showing the branched 
alimentary canal: 2. Anterior extremity of Distoma lanceolatum , enlarged; a An¬ 
terior sucker; b Posterior sucker; cGenerative pore; d Gullet; e e Bifurcating aliment¬ 
ary canal (after Owen). 


of the tissues of the body, and is never provided with a dis¬ 
tinct anus. The best known of the Trematoda is the common 
liver-fluke (Bistoma hepaticum , Fig. 40, 1), which inhabits 
the gall-bladder or ducts of the liver in sheep, and is the cause 
of the disease known as the rot. In form it is ovate, flat¬ 
tened on the two sides, and presenting two suckers, of which 
the anterior is perforated by the aperture of the mouth. A 
branched water-vascular system is present, and opens pos¬ 
teriorly bv a small aperture. The alimentary canal bifurcates 
shortly behind the mouth, the two divisions thus produced 
being much branched, and terminating posteriorly in blind 
extremities. In Bistoma lanceolatum (Fig. 40, 2) the intes¬ 
tine is divided into two branches, but these are simple tubes, 
and are not branched. 







SCOLECIDA. 


113 


Order III. Turbellaria. —The animals included in this 
order differ altogether from the Trematoda and Tceniada in 
being almost all aquatic in their habits and being all non- 
parasitic. They never possess sucking-disks or hooklets, and 
their integument is always furnished with vibrating cilia. A 
water-vascular system is always present, but it appears some¬ 
times not to communicate with the exterior. The alimentary 
canal is sometimes simply hollowed out of the tissues and 
destitute of an anus, as in the Trematoda , or at other times 
suspended in a free space (body-cavity) and furnished with an 
anus. It may be simple or much branched. 

The best known of the members of this order are certain 
little jelly-like, soft-bodied, ovate, or elliptical creatures, which 
are commonly found in fresh water or on the sea-shore, and are 
known as Planarians. The skin in these curious little ani¬ 
mals (Fig. 41, 1, 2) is richly furnished with cilia, and also 
contains numerous cells which have been compared to the 



gn 


Fig. 41. —Turbellaria. 1. Planaria torva: m Mouth; g Nerve-ganglion; e Eyes; on 
Ovary; t Spermarium; g n Genital opening-: 2. Planaria lactea, showing the branched 
intestine: 8. Larva of one of the marine Turbellarians: 4. Pilidium , the larva of one 
of the Nemertidai. 

“nettle-cells” of the Coelenterata. The intestine may be 
either straight or branched, but always terminates behind 
in blind pouches, and is never provided with an anus. The 
water-vascular system communicates with the exterior. The 
nervous system consists of two ganglia, placed in front of the 
mouth, and united by a cord. There are generally rudimen¬ 
tary eyes or pigment-spots, which vary in number from two 
to sixteen. 

The remaining members of the Turbellaria are known as 
ribbon-worms ( Nemertidai ), and are not uncommonly found 
on the sea-shore. They differ from the Planarida in being 









114 


INVERTEBRATE ANIMALS. 


worm-like in shape, by the fact that the alimentary canal is 
furnished with a distinct anus, and by the absence of an ex¬ 
ternal opening to the water-vascular system of the adult, in 
some cases at any rate. Their development sometimes shows 
phenomena very similar to what occurs in the Echinodermata , 
the larva (Fig. 41, 4) being a free-swimming, ciliated organ¬ 
ism, of which only a portion is employed in producing the 
adult animal, the remainder being cast off as useless. 

Order IV. Acanthocephala (Gr. akantha , thorn ; ke- 
phale, head).—The “ thorn-headed worms” included in this 
order are all internal parasites. They are worm-like in shape, 
marked with transverse wrinkles, and destitute of any mouth 
or alimentary canal. The anterior extremity of the body forms 
a kind of proboscis or snout, which is armed with recurved 
hooks, and has placed at its base a single nervous ganglion. 
Beneath the skin is a net-work of canals, containing a clear 
fluid, and believed to represent the water-vascular system. 
The thorn-headed worms include some of the most formidable 
parasites with which we are as yet acquainted, the best known 
being the various forms of Echinorhynchus , which are found 
inhabiting the alimentary canal in many mammals, birds, and 
fishes, but not as yet in man. 

Order V. Gordiacea.— The Gordiacea , or “hair-worms,” 
are thread-like parasites which in the earlier stages of their 
existence inhabit the bodies of various insects, chiefly beetles 
and grasshoppers. They possess a mouth and alimentary 
canal. The sexes are distinct, and they leave the bodies of 
the insects which they infest to breed, subsequently deposit¬ 
ing their eggs in long chains either in water or in some moist 
situation. In form the Gordiacea are singularly like hairs, and 
they often attain a length very many times greater than that 
of the insect in which they live. 

Order VI. Nematoda (Gr. nema , a thread).—In this 
order are the “ round-worms ” and “ thread-worms,” both of 
which are parasitic, together with a number of worms which 
lead a permanently free existence. All the Nematoda (Fig. 
42) are elongated and cylindrical or thread-like in shape. 
They possess a distinct mouth, and an alimentary canal which 
is freely suspended in an abdominal cavity, and which termi¬ 
nates in a distinct anus. They possess a system of canals 
which are believed to represent the water-vascular system; 


SCOLECIDA. 


115 


and the nervous system is in the form of a gangliated cord 
surrounding the gullet, and sending filaments backward. 
Among the best known of the parasitic Nematodes are the 
common round-worm (Ascaris lumbricoides) and the thread¬ 
worm ( Oxyuris) of the human subject, both of which inhabit 
the alimentary canal, and the guinea-worm (Filarid), which 
spends a portion of its existence in 
the cellular tissue of man, especially 
of the legs, and which attains a 
length of several feet. More dan¬ 
gerous than any of these is the 
Trichina , which spends its immature 
stages encysted in the muscles of 
some such animal as the pig, and 
only attains maturity and becomes 
capable of producing eggs, when in¬ 
troduced into the alimentary canal 
of some other warm-blooded verte¬ 
brate animal. When this takes 
place, a train of symptoms are 
originated which sometimes re¬ 
semble rheumatic fever, and appear 
to be very generally fatal. 

Of the free Nematode worms, 
which are never parasitic at any 
time of their lives, about two hun¬ 
dred species have been described, 
most of which inhabit fresh water 
or the shores of the sea. One of 
the most familiar is the so-called 
“ vinegar - eel ” (Anguillula aceti , 

Fig. 42, A). 

Fig. 42.—Nomatoda. A. Vinegar-eel 

Order VIII. Rotifera (Lat. nKSh 

rota , wheel; fero , I carry). The living in stagnant water. 

Rotifera , or “wheel-animalcules,” 

derive their popular name from the fact that the anterior end 
of the body is furnished with one or two circlets of cilia 
(Fig. 43) which, when in motion, vibrate so rapidly as to 
produce the illusory impression of a quickly-rotating toothed 
wheel . The Rotifera are almost all aquatic, and are mostly 
inhabitants of fresh water. They are all microscopic in size, 
none attaining a greater length than one-thirty-sixth of an inch. 
In the females there is a distinct mouth, intestinal canal, and 







116 


INVERTEBRATE ANIMALS. 


anus. A nervous system is also present, consisting of gan¬ 
glia placed near the anterior extremity of the body and send¬ 
ing filaments backward. There is, finally, a well-developed 
water-vascular system. 

Most of the Hotifera are free-swimming, active little ani¬ 
mals (Fig. 43, A), but some are permanently fixed, as in 
Melicerta (Fig. 43, B), or in the crown-animalcule Stephano- 
ceros). They are usually simple, but they are sometimes com¬ 
posite, forming colonies. As a rule, the male and female 
Hotifera differ greatly from one another, the males being 
smaller than the females, devoid of any masticatory or diges- 



Fig. 43.—Rotifera. A. Diagrammatic representation of ITydatina senta (generalized from 
Pritchard): a Depression in the ciliated disk leading to the digestive canal; b Mouth • 
c Pharyngeal bulb with masticatory apparatus; d Stomach; e Cloaca; /Contractile 
bladder; gg Respiratory or water-vascular tubes; h Nerve-ganglion, giving filament to 
ciliated pit (&); o Ovary. B. Melicerta ringens (after Gosse). 


tive apparatus, and more or less closely resembling the young 
forms of the species. The males, in fact, merely lead a tran¬ 
sient existence, and die as soon as they have succeeded in 
fertilizing the females. The body in most cases is very dis¬ 
tinctly ringed or annulated (Fig. 43, A), but is not composed 
of distinct rings separated by partitions. The integument is 
usually provided with bundles of muscular fibres taking a 
longitudinal and transverse direction. In the free forms the 







SCOLECIDA. 


117 


anterior ciliated disk acts somewhat like the propeller of a 
screw-steamer in driving the organism through the water—in 
all cases it has the action of producing currents in the water 
by which particles of food are brought to the mouth. The 
posterior end of the body is usually developed in the free 
forms into a kind of tail or foot (Fig. 43, A), which may take 
the shape of a kind of pincers or of a little suctorial disk. 

As regards their internal anatomy, in the females of aimost 
all the 1lotifera there is a well-developed alimentary canal, 
which is completely shut off from the general cavity of the 
body. The mouth (Fig. 43, A b) opens into a dilated cham¬ 
ber (c), which contains a complicated apparatus of horny 
teeth. This in turn opens into a capacious stomach (d), con¬ 
tinued into an intestine which terminates by a chamber known 
as the “cloaca” (e), which forms the common outlet for the 
water-vascular and generative systems. In both sexes there 
is a well-developed water-vascular system consisting of a con¬ 
tractile chamber or bladder (/*), opening into the cloaca, and 
givipg origin to two complicated tubes which are known as 
the “respiratory tubes” (g g ), and which terminate near the 
anterior end of the body, apparently by blind extremities. 
The nervous system is in the form of a large double ganglion 
placed above the gullet, and having one or tw’o eye-specks 
placed upon it. The ovaries (o) constitute conspicuous organs 
in the female Hotifera , but in summer the young Rotifers ap¬ 
pear to be produced by the females without having access to 
the males. 

The Hotifera were long confounded with the Infusoria , in 
consequence of their great similarity in external appearance. 
They are, however, of an obviously much higher grade of 
structure. One of the most remarkable phenomena presented 
by the Hotifera is found in the undoubted fact that, in spite 
of their complex organization and aquatic habits, they can be 
dried, and again brought to life by the addition of a little 
water, and that this desiccation and restoration to life can be 
apparently repeated many times in succession without injury. 


SUB-KINGDOM IV.—ANNUL OS A. 


CHAPTER XII. 

Anaetheopoda. 

Sub-kingdom Annulosa. —In this sub-kingdom are com¬ 
prised an enormous number of animals which agree in the 
following characters (Fig. 44) : The body is composed of a 
number of segments or rings arranged along a longitudinal 
axis. There is a distinct alimentary canal ( b ), placed cen¬ 
trally as compared with the other organic systems, and com¬ 
pletely shut off from the general cavity of the body. The 



Fig. 44.—Diagram of an Annulose animal, a Blood-vascular or haemal system; b Digestive 
system; c Neural system. 


blood-vascular system may be absent, but, when present, it is 
always situated on the dorsal aspect of the body (a). The 
nervous system is always present, and is placed along the 
ventral surface of the body. In its typical form it consists 
of two nervous cords running along the whole length of the 
ventral surface, and having a pair of ganglia developed in 
each ring. The first pair of ganglia is always placed above 
the gullet, and the second below, so that the gullet is sur¬ 
rounded by the two cords uniting these ganglia (constituting 
the so-called oesophageal collar). The limbs (when present) 
are always turned toward the neural aspect—that is to say. 










ANARTHROPODA. 


119 


toward that side of the body upon which the nervous system 
is situated. (See also the transverse section of an Annulose 
animal, Fig. 1.) The entire sub-kingdom of the Annulosa is 
divided into two great divisions termed Arthropoda and 
Anarthropoda^ according as the body is provided with jointed 
appendages or not. In the Arthropoda. in which the body- 
rings are furnished (some or all) with jointed appendages, are 
included the Crustaceans (lobsters, crabs, etc.), the spiders and 
scorpions, the centipedes, and the insects. In the Anarthro- 
poda , in which there are no true jointed appendages, are in¬ 
cluded the spoon-worms, leeches, earth-worms, tube-worms, 
and sand-worms.* 

Division I. Anarthropoda (Gr. a, without; arthros , joint; 
podes , feet).—In this division of the Annulosa , the locomotive 
appendages are never distinctly jointed or articulated to the 
body . In this division are included two principal classes—the 
Gepliyrea and the Annelida, f 

Class I. Gephtrea. —This class is a very small one, and 
includes a number of worm-like animals, which in most re¬ 
spects are very similar to the following class of the Annelida , 
but are distinguished by having no locomotive appendages at¬ 
tached to the sides of the body. They were long placed among 



Fig. 45.—Gephyrea. Syrinx nudus (after Forbes). 


the Echinodermata , having a decided relationship to the worm¬ 
like Holotliurians. They are distinguished, however, by never 
secreting calcareous matter in the skin, and by having no 
water-vascular or ambulacral system. There can be no doubt, 

* The Anarthropoda are often united with the Scolecida into a common sub-kingdom 
under the name of Vermes; in which case the Echinodermata are retained apart in a 
special sub-kingdom. _ . , 

+ A third class has been constituted under the name of Chcetognatha for some singular 
marine animals, transparent and worm-like in form, with lateral fins at the hinder end of the 
body, and having the mouth armed with bristles. They form the genus Sagitta. 





120 


INVERTEBRATE ANIMALS. 


however, that the Gephyrea are, on the whole, very nearly 
related to the Holothurians , and it is chiefly from the total 
absence of any radiate arrangement of the nervous system and 
internal organs that they appear to be more properly classed 
with the worms. The Sipunculus or spoon-worm is found 
burrowing in the sand of many sea-coasts, or inhabiting the 
cast-away shells of univalve shell-fish. A considerable num¬ 
ber of species of this class have been recorded as occurring in 
European seas, and one of the more characteristic forms is 
figured above (Fig. 45). 

Class II. Annelida (Lat. annulus , a ring).—The Annelida 
or ringed-worms are distinguished from the preceding by the 
possession of definite segmentation, the body being composed 
of a number of rings which are all similar to each other ex¬ 
cept at the tw r o ends of the body. All the Annelida are more 
or less worm-like in shape, and in all, except the leeches, the 
segments are (some or all) provided with lateral appendages 
which mostly subserve locomotion, but which are never jointed 
to the body. In the typical Annelida each segment (Fig. 46) 


n 



Fig. 46.—Diagrammatic transverse section of a typical Annelide. d Dorsal arc; v Ventral 
arc; n Branchiae or gills; a Dorsal oar; b Ventral oar—both carrying bristles and a 
jointed filament. 


consists of two arches, termed, from their position, respectively 
the “dorsal arc” (c?), and the “ventral arc” ( v ). Each seg¬ 
ment carries a lateral process on each side, which are known 
as the “foot-tubercles” (parapodia). Each foot-tubercle in 
turn may consist of an upper piece or “ dorsal oar ” (a), and a 
lower piece or “ ventral oar ” (5), both carrying a tuft of bris¬ 
tles and a soft jointed filament. 

The nervous system consists essentially of a double gan- 
gliated chain placed along the ventral surface of the body, and 






ANARTHROPODA. 


121 


traversed in front by the gullet, so that the first ganglion lies 
above the gullet (Fig. 44). The digestive system consists of 
a mouth, generally with a protrusible proboscis, and sometimes 
horny jaws, a gullet, stomach, intestine, and a distinct anus. 
As a rule, the alimentary canal runs straight from one end of 
the body to the other without describing any convolutions in 
its course. In almost all cases the alimentary tube is placed 
in a distinct cavity, which contains a fluid with solid par¬ 
ticles in it, believed to correspond to the blood of the higher 
Annulosa. In most, if not in all, there is an additional system 
of vessels which carry a fluid containing solid particles, which 
are contractile, and which send branches to the respiratory 
organs, when these exist. This system is believed not to cor¬ 
respond to the blood-vascular system of the higher animals, 
and it has, therefore, been termed the “ pseudo-haemal” system 
(Gr. pseudos , falsity; and haima , blood). It is believed, on 
the other hand, to be truly homologous with the water-vascu¬ 
lar system of the Annuloida. Respiration is effected by the 
general surface of the body, or by distinct gills or branchiae. 
In most cases, also, there exists a series of peculiar involutions 
of the integument, which are known as the “ segmental or¬ 
gans ” or “ respiratory pouches,” and which are believed to 
be partially concerned in the respiratory process. ‘The sexes 
in the Annelida are sometimes distinct, sometimes united in 
the same individual. The embryos are almost always ciliated, 
and many of them pass through a metamorphosis. 

The Annelida may be divided as follows: 

Section A. Abranchiata. —Without gills or branchiae. 

1. Ilirudinea. —(Leeches.) 

2. Oligochceta. —(Earth-worms.) 

Section B. Branchiata.— With branchiae. 

3. Tubicola. —Tube-worms.) 

4. JErrantia. —(Sand-worms.) 

Order I. Hirudinea (Lat. hirudo , a horse-leech).—This 
order comprises only the leeches, some of which are marine, 
while others inhabit fresh water. The leeches (Fig. 47) are 
all characterized by the fact that the body is destitute of 
lateral bristles or foot-tubercles, but is provided with a suck¬ 
ing-disk at one or both extremities. In the typical forms, as 
in the common medicinal leech, there are sucking-disks at 
both ends of the body, and in those in which only the hinder 
sucker is present, the head can be converted into a suctorial 


122 


INVERTEBRATE ANIMALS. 


cavity. Locomotion is effected either by means of the alter¬ 
nate fixation and detachment of the suckers, or by a serpentine 
bending of the body. 

The body is obviously ringed or annulated, but none of 
the rings carry lateral appendages of any kind. The mouth 
is sometimes destitute of teeth, but is occasionally armed with 
complex jaws. The alimentary canal 
is short, with lateral dilatations, and 
united to the skin by means of a 
spongy vascular tissue, so that the body- 
cavity is obliterated. The pseudo - 
haemal system is well developed, and 
consists essentially of four great longi¬ 
tudinal vessels. Respiration appears 
to be effected, in part, at any rate, 
by means of the segmental organs, 
which have the form of little sacs 
opening externally by minute aper¬ 
tures. The nervous system has its 
usual form, and the ganglia in front of 
the gullet (“ prce-oesophageal” ganglia) 
give off branches to a number of simple 
eyes which are placed on the head. 
The sexes are united in the same in¬ 
dividual. 

The most familiar of the leeches are 
the common horse-leech {Hmmopsis), 
the medicinal leech (Sanguisuqa 
ssrsrSJ3SSTK officinalis, Fig. 47). The former has 
showing “lu^TJicireuii sma11 and blunt teeth, but the latter is 
toothed margin. provided with three semicircular tooth¬ 

ed jaws (Fig. 47, b , c), which meet in a 
point, and are sufficiently powerful to cut through the human 
skin. The medicinal leech is a native of fresh waters through¬ 
out the south and east of Europe, and it is imported in large 
numbers from Hungary, Bohemia, and Russia. 



Fig. 47.—Hirudinea. a The me¬ 
dicinal leech (Sanguisugci 
officinalis ), natural size ; 5 
Anterior extremity of the and 
same magnified, showing the 


Order IT. Oligoceueta. —In this order are included the 
earth-worms (Lumbricidce ), and the water-worms (JSTa'ididoe). 
They are all distinguished from the preceding by the fact 
that the body is furnished with rows of bristles which take 
the place of the foot-tubercles of the higher Annelida , and 
which are the organs of locomotion. They are distinguished 
from the higher forms by the fact that the locomotive bristles 





ANARTIIROFODA. 


123 


are comparatively few in number, hence the modern name of 
the order (Gr. oligos, few; and chaite , a bristle). In the com¬ 
mon earth-worm ( Lumbricus terrestris) the body is cylindrical, 
attenuated at both ends, and furnished with eight rows of 
locomotive bristles. The mouth is destitute of teeth, and 
opens into a gullet which leads to a muscular crop, succeeded 
by a second muscular dilatation or gizzard. The intestine is 
continued straight to the anus, and is constricted in its course 
by numerous transverse partitions springing from the walls 
of the body-cavity. The pseudo-haemal system is well de¬ 
veloped ; and there exists in even greater numbers than in 
the leeches the series of segmental organs, or lateral pouches, 
which open externally by pores. The Naididce are chiefly 
noticeable on account of their power of producing fresh indi¬ 
viduals by a process of budding before they attain sexual 
maturity. One of the commonest of them is a little worm 
which occurs abundantly in many pools and streams ( Tubifex 
rividorum ), and which exhibits a fine red color, owing to the 
pseudo-haemal system being visible through the transparent 
integument. 

Order III. Tubicola. —The Annelides included in this 
group derive their name from the 
fact that they have the power of 
protecting themselves by means of 
tubes (Lat. tuba , a tube; and colo^ 

I inhabit). In some cases (Fig. 

48) the tube is composed of car¬ 
bonate of lime, and is a genuine 
secretion from the body. In all 
the Tubicola the respiratory organs 
are in the form of branched fila¬ 
mentous external gills, in which 
the fluid of the pseudo-haemal sys¬ 
tem is subjected to the action of 
the outer water. They are, there¬ 
fore, “ branchiate ” Annelides. As 
they live in tubes, however, and 
do not voluntarily expose more 
than the anterior end of the body, 
the branchiae are all placed on or near the head. The filaments 
of which the gills are composed (Fig. 48, a) are richly ciliated, 
and, as the pseudo-haemal fluid is usually red, they have gen¬ 
erally a beautiful scarlet color. 





Fig. 48.—Tubicola. a Serpula con- 
tortuplicata, showing the bran¬ 
chiae and operculum; b /Spirorbis 
communis. 


124 


INVERTEBRATE ANIMALS. 


The most familiar of the Tubicola is the Seipula (Fig. 
48, a), the contorted and winding tubes of which must be 
known to every one as occurring on shells or stones on the 
sea-shore. One of the cephalic filaments in Serpula is much 
developed, and its extremity forms a kind of conical plug 
which serves to close the mouth of the tube when the animal 
is retracted within it. In Spirorbis (Fig. 48, b) the shelly tube 
is coiled into a flat spiral, which is fixed to some solid object. 
It is of extremely common occurrence on the fronds of sea¬ 
weed, and on other submarine objects. 

Order IV. Erraotia. —The Annelides comprised in this 
order are called “ errant ” (Lat. erro , I wander), or “ roving,” 
from the fact that they all lead a free existence, and are never 
confined in tubes. They have always lateral unjointed ap¬ 
pendages, or foot-tubercles (Fig. 49), which carry tufts of 



I A 

Fig. 49—Errant Annelides. A. Hairy Bait (Kephthys)', B. Sea-Mouse (Aphrodite ); C. 
Lobworm (Arenicola). (After Gosse.) 

bristles and a soft, jointed filament. The anterior rings of 
the body are usually so modified as to form a sort of "head, 
which is provided with eyes and with two or more feelers, 
which differ from the antennae of insects and Crustaceans in 
not being jointed. The mouth is placed on the inferior sur¬ 
face of the head, and is sometimes furnished with one or more 
pairs of horny jaws, which work from side to side. The upper 





ANARTHROrODA. 


125 


part of the alimentary canal is muscular, and can be turned 
inside out, or protruded beyond the true opening of the 
mouth. The pseudo-haemal system is well developed, and its 
contained fluid is mostly red. Respiration is effected by ex¬ 
ternal processes, gills, or branchiae, arranged in tufts placed 
along the sides or back of the body, and not confined to the 
immediate neighborhood of the head, as in the Tubicola. The 
sexes are in different individuals, and the young pass through 
a metamorphosis. 

Among the best known and commonest of the Errant Anne- 
lides are the common lob-worm (Arenicola piscatorum) of our 
coasts, which is constantly used by fishermen for bait; and the 
sea-mice (Aphrodite and Polynoe ), some of which attain a large 
size, and are conspicuous for their iridescent bristles. Other 
less abundant forms may be readily obtained by searching 
under stones at low water. 


CHAPTER XIII. 


Arthropoda. 

Division II. Arthropoda or Articulata. —The members 
of the sub-kingdom Annulosa comprised under this head are 
generally known as Articulate animals, or as Arthropoda (Gr. 
arthros , a joint; and podes , feet). They are all distinguished 
by the possession oi jointed appendages articulated to the body. 
The body is composed of a series of distinct rings or segments 
(technically called “ somites ”) arranged longitudinally one be¬ 
hind the other; The skin is more or less completely hardened 
by a horny deposit of “ chitine,” with or without lime, so as to 
form a resisting shell, to the inner surface of which the muscles 
are attached. There is consequently no necessity for any in¬ 
ternal skeleton. The nervous S 3 r stem in the young of all 
Articulate animals has its typical form of a chain of ganglia 
placed along the ventral surface of the body, and traversed in 
front by the gullet. In the adult, however, this typical state 
of the nervous system is often lost or modified. The blood- 
circulatory system may be absent; but, when it is present, it is 
placed dorsally (Fig. 44), and consists of a true blood-system 
containing corpusculated blood, and furnished with a contractile 
cavity or heart. Respiration is sometimes effected simply by 
the general surface of the body, but there are generally special 
organs adapted for breathing air, either directly or through the 
medium of water. Jointed appendages are always present, and 
may be developed from any segment of the body. 

The Arthropoda are divided into four great classes—viz., 
the Crustacea (crabs, lobsters, etc.), the Arachnida (mites, 
spiders, and scorpions), the Myriapoda (centipedes and gally- 
worms), and the Insecta (or true insects). These are roughly 
distinguishable from one another by the following charac¬ 
ters 


ARTIIROPODA. 


127 


1. Crustacea. —Animal more or less truly aquatic; respiration by gills, 
or by the general surface of the body; two pairs of antennae (feelers); loco¬ 
motive appendages more than eight in number, borne by the segments of the 
thorax, and usually of the abdomen also. 

2. Arachnida. —Respiration aerial, by pulmonary sacs, by air-tubes 
(tracheae), or by the general surface of the body; head and thorax amalga¬ 
mated ; antennae ( as such), absent; legs eight; abdomen without jointed 
appendages. 

3. Myriapoda. —Respiration by air-tubes (tracheae) ; head distinct; re¬ 
mainder of the body composed of nearly similar segments; one pair of 
antennae; legs numerous. 

4. Insecta. —Respiration by air-tubes (tracheae); head, thorax, and 
abdomen distinct; one pair of antennae; three pairs of legs borne on the 
thorax; abdomen destitute of limbs ; generally two pairs of wings on the 
thorax. 



CHAPTER XIV. 


Crustacea. 

Class I. Crustacea (Lat. crusta , a crust, or external 
shell).—The members of this class are commonly known as 
crabs, lobsters, shrimps, prawns, king-crabs, barnacles, acorn- 
shells, wood-lice, etc. They are nearly allied to the succeeding 
class of the Arachnida (spiders and scorpions), but are dis¬ 
tinguished by their adaptation to a more or less purely aquatic 
life, by having jointed appendages upon the hinder segments 
of the body (abdomen), and by the possession of two pairs of 
antennas. As a class, the Crustacea are distinguished by 
being usually furnished with branchiae or respiratory organs 
adapted for breathing air dissolved in water, by having more 
than four pairs of legs, by having a well-developed chitinous 
or partially calcareous “crust” or external skeleton, by the 
fact that some of the appendages are generally so modified as 
to act as organs of mastication, and by passing through a meta¬ 
morphosis before attaining their adult condition. 

The body in a typical Crustacean is composed of twenty-one 
(or, according to some writers, twenty ) distinct segments or 
somites, placed one behind the other. These segments are 
distributed in three distinct divisions, known respectively as 
the “ head,” the “ thorax ” or chest, and the “ abdomen ” or 
tail, each of which is usually regarded as being composed of 
seven segments. In very many cases, however, the fourteen 
segments belonging to the head and chest are amalgamated 
together into a single mass, which is termed the “ ceplialo- 
thorax,” thus leaving seven segments to the abdomen. It 
will be unnecessary, however, to dwell here longer upon the 
structure of the Crustacea , as the general morphology of 
the class will be given at somewhat greater length in speak¬ 
ing of the lobster. The classification, also, of the Crustacea 


CRUSTACEA. 


129 


is so complex that it will be as well to omit altogether the 
less important orders, merely giving the names and leading 
characters of these in an appendix. It has also been thought 
advisable to invert the usual order here adopted, and to com¬ 
mence with the consideration of the highest sections of the 
class first. 

Order Decapoda. —The Crustacea included in this order 
derive their name from the fact that they all possess five pairs 
of legs (Gr. deka , ten; podes , feet). They belong to a large 
section known as the “ stalk-eyed ” Crustaceans, from the fact 
that the eyes are supported by long, movable stalks. They 
include the lobsters, shrimps, cray-fish, crabs, hermit-crabs, and 
other forms, and are the most highly organized and most familiar 
of the whole class of the Crustacea. They are divided into 
three very well marked groups or tribes, all of which can be 
exemplified by the well-known British species. 

A: Macrura .—The name of Macrura (Gr. makros , long; 
and oura, tail) is given to those ten-footed Crustaceans which 
have a long and well-developed tail. Among these are the 
■lobster, shrimp, prawn, and cray-fish, of which the lobster may 
be seleoted as a good typical example. 

In the lobster (Fig. 50) the body is at once seen to be 
composed of two parts, familiarly called the “head” and 
“ tail.” The so-called head is covered by a great shield termed 
the “carapace” (Fig. 50, ca ), and it is in reality the cephalo- 
thorax, being composed of the amalgamated segments which 
belong to the true head and to the thorax. The so-called 
tail is really the abdomen, and it is composed of a number of 
segments which are not immovably united together, as in the 
cephalo-thorax, but are movably jointed together. The vari¬ 
ous appendages of the animal are arranged in pairs on the 
under surface of the body; and, where the segments are com¬ 
pletely amalgamated (as in the cephalo-thorax), their existence 
may, nevertheless, be determined by the presence of a pair of 
appendages. The first segment of the head carries a pair of 
compound eyes, made up of a number of simple lenses aggre¬ 
gated together, and supported upon long and movable eye- 
stalks. Behind these come two pairs of jointed organs of 
touch, which are known as the “ antennae.” The front pair is 
much smaller than the hinder pair, and they are known re¬ 
spectively as the “lesser antennae,” or “antennules,” and 
the “great antennae.” Behind these, again, comes the mouth, 
which is placed on the under surface of the head, and is pro- 


130 


INVERTEBRATE ANIMALS. 


vided with a complicated series of masticatory organs. It is 
unnecessary to describe these minutely, but it should be 
noticed that they are all modified limbs, and therefore differ 



Fig. 50.—Common Lobster (Romanis vulgaris). 1. First pair of legs, constituting the 
great nipping-claws; 2 and 3. Second and third pairs of legs, also ending in nipping- 
claws ; 4 and 5. Last two pairs of legs; a Smaller antennae; ga Greater antennae; ca 
Carapace. 


altogether from the jaws of the Vertebrate animals. That 
this is their real nature is shown most obviously in the hind¬ 
most pairs of these jaws, which are so little altered from ordi¬ 
nary legs that they are known as “ foot-jaws.” The last five 











CRUSTACEA. 


131 


segments of the thorax carry five pairs of walking-legs, hence 
the name Decapoda applied to the order. Of these legs, the 
first three pairs have their extremities converted into nipping- 
claws or “ chelae,” and the first pair is much larger than the 
others, and constitutes the well-known great claws of the lob¬ 
ster. The last two pairs of legs simply terminate in pointed 
extremities, and not in pincers. The segments of the abdo¬ 
men, with the exception of the hindmost, carry each a pair of 
paddle-like appendages, which are used in swimming, and are 
called the “swimmerets.” The last pair of swimmerets are 
attached to the last segment but ohe, and are very greatly ex¬ 
panded, so as to form a very powerful tail-fin. The last seg¬ 
ment of all is known as the “ telson,” and is not provided with 
any lateral appendages. 

The mouth in the lobster leads by a short gullet into a 
globular stomach, which is furnished with a calcareous appa¬ 
ratus for grinding down the food, commonly called the “lady 
in the lobster.” The intestine is continued backward from 
the stomach without convolutions, and opens by a distinct 
anus placed in front of the telson. A well-developed liver is 
also present. The heart is placed dorsally, and is filled with 
aerated blood derived from the gills, which it propels through 
every part of the body. The gills, or branchiae, are pyrami¬ 
dal bodies attached to the bases of the legs, and placed in 
a kind of chamber formed beneath the great shield, or cara¬ 
pace, on each side of the body. They consist each of a central 
stem supporting numerous lateral branches, and they are richly 
supplied with blood. The water which fills the gill-chambers 
is constantly renewed by the movements of the legs, and thus 
the gills are kept constantly supplied with fresh water. The 
nervous system is placed along the ventral surface of the body, 
and has its usual form. The organs of sense are the two pairs 
of feelers or antennae, the compound eyes, and two organs of 
hearing. 

B. Anomura .—The most familiar members of this tribe 
are the hermit-crabs ( Paguridce ) which occur so commonly on 
every shore. They are distinguished by the fact that the ab¬ 
domen is quite soft, and is not protected by a chitinous crust. 
The animal, therefore, is compelled to protect the defenceless 
part of the body in some artificial manner, and this it effects 
by appropriating the empty shell of some dead mollusk, such 
as the common periwinkle or whelk. The abdomen is pro¬ 
vided with special appendages to enable the intruder to re¬ 
tain firm hold of his borrowed dwelling, at the same time that 


132 


INVERTEBRATE ANIMALS. 


he can change it at will when too small or otherwise incon¬ 
venient. The first pair of legs are developed into pretty 
powerful nipping-claws or chelse, and one of them is always 
much larger than the other, and acts as a kind of plug, block¬ 
ing up the entrance of the shell when the animal is retracted 
within it. 

C. Brachyura .—The decapod Crustaceans included in 
this tribe are familiarly known as crabs, and they derive their 
name of Brachyura (G. brachus , short; and oura, tail) from 



Fig. 51.— Brachyura. The Spiny Spider-crab (3Iaia sguinado). 


the rudimentary condition of the abdomen. The abdomen, in 
fact, is not onty extremely short, but it is always tucked up 
beneath the greatly-developed cephalo-thorax, so that it is not 
visible at all, except when the animal is looked at from below 
(Fig. 51). The crabs are very various in their habits, but they 
are mostly denizens of the shore, hiding beneath stones or sea- 


CRUSTACEA. 


133 


weed, in cracks of rock, or in pools near the line of low water. 
Some of them, however, can swim with tolerable activity, and 
some of them (the land-crabs) even live habitually inland. 
One group, the “ pea-crabs,” is distinguished by the singular 
habit of living semi-parasitically within the shells of bivalve 
mollusks, such as the great horse-mussel. 

The young or larval crab is exceedingly unlike the adult, 
and has a long and well-developed abdomen, thus approximat¬ 
ing to the type of structure which is permanently retained in 
the Macrura. 


Order Isopod a (Gr. isos , 
order are a number of Crus¬ 
taceans of which some in¬ 
habit the sea, others are 
parasitic in their habits, and 
others are terrestrial. The 
best known are the common 
wood-lice ( Oniscus , Fig. 52), 
which are found so com¬ 
monly under stones, or in 
the crevices of old walls. 
The Isopods all belong to 
a group of Crustaceans in 
which the eyes are not sup¬ 
ported upon stalks, and they 
are therefore said to be “ses- 
sile-eyed.” The head is dis¬ 
tinct from the segment bear¬ 
ing the first pair of feet. The 
thoracic feet are all similar 
to one another, and the bran¬ 
chiae are developed on the 
abdominal legs. 


equal; podes , feet).—In this 



Fio. 52.—Isopoda. Wood-lice {Oniscus). 


Order Merostomata. —In this order are only the living 
king-crabs ( Limulus ), and some large extinct forms nearly 
allied to them. They are all distinguished by the fact that 
the appendages which are placed round the mouth act by 
their bases as jaws, but have their extremities developed into 
swimming-paddles, walking-feet, or nipping-claws. 

The King-crabs or Horseshoe crabs (Fig. 53) constitute a 
special group called Xiphosura (Gr. xiphos, a sword; and 
1 








134 


INVERTEBRATE ANIMALS. 


our a, tail), from the fact that the end of the abdomen is 
furnished with a long sword-like spine (Fig. 53, t). The 
mouth is surrounded by six pairs of appendages, the bases of 
which are spinous and act as jaws, while their free extremities 
are developed into nipping-claws or chelae. The whole of the 
upper surface of the body is protected by a kind of buckler, 
composed of an anterior semicircular shield, and a posterior 
somewhat hexagonal plate, the under surface of which carries 




branchial plates, while the sword-like telson is jointed to its 
hinder margin. The king-crabs attain a large size, and are 
often called “ Molucca crabs ” from their occurrence in the 
Moluccas. Both the eggs and the flesh are eaten by the 
Malays. 

Closely allied to the king-crabs is the extinct family of the 
Eurypterida , an example of which is figured above (Fig. 54). 
This species is supposed to have attained a length of probably 
six feet, but other forms were very much smaller. 












CRUSTACEA. 


135 


Order Trilobita. — The Trilobites constitute another 
wholly extinct order of the Crustacea , and deserve a short 
notice from their great geological importance. The} 7 derive 
their name from the fact that the body exhibits a more or less 
conspicuous division into a central and two lateral lobes (Fig. 
55, 1). The entire shell or crust is composed of an anterior 



Fig. 55.— Trilobita. 1. Angelina SedgvAckii; 2. Diagram of the cephalic shield of a 
Trilobite (after Salter). 


semicircular shield, covering the head (Fig. 55, 2), a series of 
movable rings, constituting the thorax, and a tail-piece com¬ 
posed of amalgamated segments, and representing the abdo¬ 
men. On the under surface of the shell nothing had ever 
been discovered except the upper lip, but recently traces of 
limbs have been made out. The cephalic shield usually 
bears a pair of compound eyes (Fig. 55, 2 o), but these are 
sometimes wanting. It is probable that most of the Trilo¬ 
bites possessed the power of rolling themselves up into a ball, 
much as our modern wood-lice. The Trilobites are only known 
as occurring in the older rocks of the earth’s crust, and they 
are chiefly characteristic of the period known to geologists as 
the “ Silurian.” 

Orders Cladocera, Copepoda, and Ostracoda. —These 
orders deserve mention more from the extreme abundance of 
their commoner forms than for any other reason. They in¬ 
clude a number of minute Crustaceans, most of which are 
commonly called “ water-fleas,” and abound in fresh waters in 
most parts of the world. They are, however so small that, 
though visible to the naked eye, they can only be satisfac¬ 
torily examined under the microscope. As an example of the 




136 


INVERTEBRATE ANIMALS. 


Gladocera may be taken the “ branched-horned water-flea ” 
(Daphnia pulex , Fig. 56, 5), thousands of which may be 
captured in any pond in summer. In this pretty little species 
the whole body is enclosed in a bivalve shell, which is so 
transparent that the whole organization of the animal is clearly 
visible through it. The head is distinct, and carries a single 



Fig. 56.—Fresh water Entomostraca. a Cypris tris - striata ; b Daphnia pulex; 
c Cyclops quadricornis. , 


eye. The greater antennm are branched. The males are 
smaller than the females, and much fewer in number; and it 
appears to be a well-established fact that the female, when 
once fertilized by the male, can not only lay eggs for the rest 
of her life, but can transmit the power of producing fertile 
ova to her young for several generations. Of the Gopepoda 
one of the commonest is the Cyclops (Fig. 56, c), in which 
the cephalo-thorax is covered by a shield, and there is a well- 
developed abdomen. The female carries on either side a kind 
of pouch or ovisac, in which the eggs remain till they are 
hatched. The little Ostracoda (Fig. 56, a) are all minute 
Crustaceans, which occur in both fresh and salt water. They 
are distinguished by the fact that the body is entirely enclosed 
in a shell, which is made up of two lateral halves or valves. 
The valves of the shell are united by a membrane along the 
back, but can be opened below, so as to allow of the protrusion 
of the feet. 


Order Cirripedia. —The last order of Crustacea which re¬ 
quires mention is that of the Cirripedia (Lat. cirrus , a curl; 
and pes , foot), comprising the so-called barnacles and acorn- 



CRUSTACEA. 


137 

shells, both extremely unlike Crustaceans to look at. All the 
Cirripedes are distinguished by the fact that, while they are 
quite free when young, and very similar to some of the little 
Crustaceans just described, w 7 hen adult they are immovably 
fixed by their heads to some solid object. In this fixed con¬ 
dition the body and internal organs are, in most cases, pro¬ 
tected by means of a calcareous shell, composed of many pieces, 
and the only part of the body which remains movable is the 
legs, which are constantly thrust out of the shell and again 
drawn in in quest of food. The Cirripedia were formerly de¬ 
scribed as “ multivalve ” shell-fish (Mollusca ), owing to their 
possession of a regular calcareous shell. Two distinct types 
of structure are known among the Cirripedia (Fig. 57), con¬ 
stituting the two families of the barnacles (Lepadidoe), and 
the acorn-shells ( Balanidce ). 

In the barnacles (Fig. 57, 5), the anterior end of the body 



is much elongated, and is converted into a kind of stalk, by 
means of which the animal is attached to some solid object, 
such as a rock, a floating log of timber, or even some marine 
animal. In the acorn-shells (Fig. 57, a ), which occur in 
myriads upon every solid object between tide-marks, there is 
no stalk, but the head is firmly cemented to the centre of a 
membranous or shelly plate. The body is enclosed in a limpet¬ 
shaped or conical shell, composed of several pieces, and having 
an aperture at its summit. This opening is closed by a mov¬ 
able lid, and from it the animal can protrude its delicate legs 
or “ cirri,” which look like a “ glass hand,” and are constantly 
employed in sweeping the water in search of food. 

In accordance with the fixed condition of the adult, almost 
all the Cirripedia are hermaphrodite, possessing both male 






138 


INVERTEBRATE ANIMALS. 


and female organs of reproduction. In some cases, however, 
males exist, but these are much smaller than the females, and 
quite different to them in appearance, and they spend their 
existence within the shell of the female. 

Appendix, giving the remaining Orders op Crustacea. 

Order Phizocephala. —Minute Crustaceans, free when young, but when 
adult parasitically attached to the abdomen of various crabs. When adult 
they are completely deformed, destitute of limbs, and attached to their host 
by means of numerous branched tubes or roots which ramify deeply among 
the internal orgaus. Ex. Peltogaster. 

Order Ichthyophthira. —Minute Crustaceans, free when young, but when 
adult parasitic upon various kinds of fishes; adult usually deformed and 
soft; young with eyes and swimming-feet. Ex. Lerncea. 

Order Phyllopoda. —Thoracic feet leaf-like and acting as branchiae. Ex. 
Apus. 

Order Lcemodipoda. —Eyes sessile ; abdomen rudimentary; respiration 
by means of little vesicles attached to the thoracic segments or legs. Ex. 
Cyamus (the whale-louse). 

Order Amphipoda .—Eyes sessile; abdomen well developed ; respiratory 
organs in the form of vesicles attached to the thoracic limbs. Ex. Sand- 
hopper ( Talitrus ); Fresh-water shrimp ( Gammarus ). 

Order Stomapoda. —Eyes stalked; gills unprotected, usually suspended 
beneath the abdomen. Ex. Locust-shrimp ( Squilla ). 


CHAPTER XV. 


Arachnid a. 

Class II. Arachnida (Gr. Arachne , a spider).—This class 
includes the mites, ticks, scorpions, and spiders, and, as a 
whole, is very nearly related to the preceding. The Arachnida , 
however, are distinguished from the Crustacea by being adapted 
in most cases for a strictly terrestrial life, so that when any 
distinct breathing-organs are present these are never in the 
form of gills, but are always either pulmonary sacs or air- 
tubes {tracheae). In none of the Arachnida , further, are there 
ever more than four pairs of legs, and the segments of the ab¬ 
domen never carry limbs of any sort. The eyes are always 
sessile, and never supported upon stalks; if antennae exist 
at all, they are much modified, and the head is always amal¬ 
gamated with the thorax , so as to form a ceplialo-thorax. 

The integument usually produces chitine more or less 
abundantly, so as to constitute a resistent shell; but in some 
cases the skin remains permanently soft. The mouth is situated 
in the anterior portion of the body, and in the higher forms is 
furnished with a pair of prehensile jaws, called “ mandibles,” 
a pair of chewing-jaws, called “ maxillae, and a lower lip. In 
the scorpions an upper lip is present as well. In the true 
spiders each mandible terminates in a sharp movable hook, 
perforated by a canal which communicates with a poison-gland 
situated near its base. By means of this poisonous fluid the 
spiders kill such animals as they capture. In the scorpions 
the mandibles are short, and terminate in strong pincers. In 
them, too, the maxilke are furnished with enormously-de¬ 
veloped nipping-claws or chelae.* In all the Arachnida the 
mandibles are believed to correspond to the antennae of the 

* These nipping-claws in the scorpions are produced not by the maxillae themselves, hut 
by two appendages to the maxillae, which are known as “maxillary palpi.” 


140 


INVERTEBRATE ANIMALS. 


Crustacea. In the lower Arachnida , such as the ticks, the 
organs of the mouth are modified to enable them to imbibe 
fluids. 

The mouth in the Arachnida opens into a pharynx, which 
is of extraordinarily small diameter in the true spiders, which 
live simply on the juices of their prey. The intestinal canal 
is usually short and straight, and is continued without convo¬ 
lutions to the aperture of the anus. Salivary glands are also 
present, as well as ramified tubes which are believed to act as 
kidneys. 

The circulation is maintained by means of a dorsal heart, 
which is situated above the alimentary canal. All the Arach¬ 
nida breathe air directly, and the function of respiration is 
performed by the general surface of the body (as in the lowest 
members of the class), or by branched air-tubes termed “tra¬ 
cheae,” or by distinct pulmonary chambers or sacs, or, lastly, 
by a combination of tracheae with pulmonary sacs. The tra¬ 
cheae are essentially similar in structure and function to the 
breathing-tubes of the Myriapoda and Insecta , and consist of 
tubes, which open on the surface of the body by distinct aper¬ 
tures called “ spiracles.” The walls of the tube are prevented 
from collapsing by means of a spirally-coiled thread or filament 
of chitine, which is wound round their walls within their inner 
lining. The pulmonary sacs which occur in the Arachnida 
are simple chambers formed by an inversion of the skin, which 
constitutes a number of closely-set plates or folds. The whole 
of the interior of the pulmonary sacs is richly supplied with 
blood, and air is admitted by means of minute external open¬ 
ings. 

The nervous system is of the regular articulate type, but 
the ganglia of the ventral chain are often massed together in 
particular situations. In no case are compound eyes present; 
and, when distinct organs of vision-exist, these are in the form 
of from two to eight simple eyes. 


Orders of the Arachnida. 

Order I. Podosomata. —In this order are included the 
“ Sea-spiders,” which are wdiolly marine, and were long be¬ 
lieved to be referable to the Crustacea on this account. As 
they have no respiratory organs of any kind, the question can¬ 
not be definitely settled, but they have no more than four 
pairs of legs, and would therefore seem to be properly refer¬ 
able to the Arachnida . In some forms the legs attain an ex- 


ARACHNIDA. 


141 


traordinary length, and contain prolongations from the storm 
ach. They are all grotesque-looking animals, found at low 
water upon stones or marine plants, or parasitically attached 
to marine animals. One of the commonest forms is figured 
below (Fig. 5H, «)• 

Order II. Acarina. —The most familiar members of this 
order are the Mites and Ticks (Fig. 57|, b, c). They are dis¬ 
tinguished by the fact that the abdomen is amalgamated with 
the ceplialo-thorax to form a single mass. Respiration is ef¬ 
fected by the general surface of the body or by air-tubes 
(tracheae). 

The habits of the mites are extremely varied. Some are 
found upon different plants (Fig. 57-J-, b ); others are parasitic 
upon water-insects when young, but swim about freely when 
adult (Fig. 57J, c ); others are permanently parasitic upon 


Fig. 57%. —Arachnida. a Pycnogonum littorale; b Tetranychvs telarius, one of the • 
“Sociable” mites; c Ilydrachna gloibulus , one of the “Water-mites.” 



other animals, such as sheep, dogs % insects, etc.; and others 
inhabit decaying provisions, as is the case with the well-known 
“cheese-mite” (Acarus domesticus). Two species have a con¬ 
siderable medical interest as attacking man. One of these 
causes the skin-disease which is known as the “ itch,” and the 
other is found inhabiting certain glandular follicles of the 
skin, probably without an exception even in favor of the most 
cleanly people. 

Order III. Pedipalpi. —In this family are the most for¬ 
midable of all the Arachnida —namely, the Scorpions. They 
are all distinguished by the fact that the abdomen is divided 
into distinct segments, and is continued into the ceplialo- 
thorax without any well-marked boundary or constriction. In 


142 


INVERTEBRATE ANIMALS. 


the true scorpions the end of the abdomen (Fig. 58) is com¬ 
posed of a hooked telson, which is perforated for the duct of a 
poison-gland, situated at its base. It is by means of this that 
the scorpions sting; and the poisonous fluid which they secrete 



Fig. 58. —Scorpion (reduced). 


is sufficiently powerful to render their wounds troublesome 
and painful, if not positively dangerous. The mandibles in 
the scorpions, as already said, are developed into pincers, and 
the so-called “ maxillary palpi ” constitute powerful nipping- 
claws. The respiratory organs are in the form of pulmonary 
sacs, four on each side, opening on the under surface of the 
abdomen by as many distinct apertures or spiracles. 

The scorpions live in the w T armer regions of the temperate 
zone and in tropical countries, and are generally found hiding 
under stones or in crevices of walls. Their sting, though 
much exaggerated, is certainly capable of producing very un¬ 
pleasant symptoms.* 

Order IV. Araneida. —In this order are the true Spiders, 
readily distinguished from the insects, with which they are 
popularly confounded, by having four pairs of legs, as well as 
by other characters. In all the true spiders (Fig. 59) the seg¬ 
ments of the thorax and head are united to form a single mass 
or cephalo-thorax, to which the soft and unsegmented ab¬ 
domen is joined by a constricted stalk, or neck. Respiration 
is effected by means of pulmonary sacs, usually conjoined with 
tracheae. The pulmonary sacs are two or four in number, and 
open on the surface of the abdomen by as many apertures. 

* Nearly allied to the Scorpions are the so-called “ Harvest-spiders” (Phalangidce), and 
the diminutive “Book-scorpion” (Chebifer), which is commonly to be found among old 
books. 


ARACHNID A. 


143 


The head bears from six to eight simple eyes; the mandibles 
are hooked, and carry the duct of a poison-gland; and the 
maxillary palpi are not developed into nipping-claws. The 
spiders are all predaceous and rapacious animals, and many of 



Fig. 59.—Araneida. Theridion riparion (female). 


them possess the power of constructing webs, either for the 
capture of their prey, or simply for lining their habitations. 
For the production of the web, spiders are furnished with 
special glands, situated at the extremity of the abdomen. The 
secretion of these glands is a viscid fluid, which hardens rapid¬ 
ly on exposure to air, and which is cast into its proper thread¬ 
like shape by passing through what are called the “spin¬ 
nerets.” These are little conical or cylindrical organs placed 
at the end of the abdomen, and perforated by a number of ex¬ 
tremely minute tubes, through which the secretion of the 
glands has to pass before reaching the air. Many spiders, 
however, do not construct any web, unless it be for their own 
habitations, but simply hunt their prey for themselves. 

The spiders are oviparous, and their young pass through 
no metamorphosis, but they cast their skin, or “ moult,” re¬ 
peatedly before they attain the size of the adult. 


CHAPTER XVI. 


MYRIArODA. 

Class III. Myeiapoda (Gr. murios, countless; podes, 
feet).—This class is an extremely small one, and includes only 
the Centipedes and the Millipedes. In all the Myriapoda the 
head is distinct, and not amalgamated with the thorax. There 
is no clear boundary-line between the thorax and the ab¬ 
domen, both being composed of nearly similar segments. The 
body, with one exception, always consists of more than twenty 
rings, and the hinder segments, which correspond to the ab¬ 
domen, always carry locomotive appendages, whereas the 
abdominal rings in Arachnida and Insecta are always des¬ 
titute of locomotive appendages. One pair of Cintennce is 
present, and the number of the legs is always more than eight 
pairs. Respiration is carried on by branched air-tubes or 
tracheae. 

In most of their characters the Myriapoda closely re¬ 
semble the true insects, with which, indeed, they are not un¬ 
commonly classed. The true insects, however, always have 
the head, thorax, and abdomen, distinct from each other, and 
have never more than three pairs of legs. In most of the 
Myriapoda the young, or “ larvae,” are more like insects than 
the adult, since they have only three pairs of legs, or are alto¬ 
gether destitute of feet. In some cases, however, the young 
Myriapod, on escaping from the egg, possesses nearly all the 
characters of the parents, except that the number of body- 
rings, and consequently of legs, is smaller, and increases with 
every change of skin (“ moult ”). The class is divided into 
two leading families, represented by the common Centipedes 
and Millipedes. 

The Centipedes (Fig. 60) are carnivorous in their habits, 
and the organs of the mouth are adapted for a life of rapine. 


MYKIAPODA. 


145 


Iu addition to the parts of the mouth proper, they have two 
pairs of “ foot-jaws,” of which the second is hooked and per¬ 
forated for the discharge of a poisonous fluid. The bite of the 
common European species is perfectly harmless to man, but 
some of the tropical forms attain a length of a foot or more, 
and are consequently able to inflict extremely severe and even 



Fig. CO.—Centipede (Seolopendra). 


dangerous bites. The true centipedes are further distinguished 
by the number of legs not being indefinitely great (usually 
from fifteen to twenty pairs), and by the fact that the antennae 
are composed of not less than fourteen joints each. 

The Millipedes (Fig. Gl) are repulsive-looking but perfectly 



Fig. 61.—Millipede (/m/us). 


innocent animals, which feed principally upon decaying vege¬ 
table matter. The body, in the ordinary millipedes, is round¬ 
ed and worm-like, and the segments are so amalgamated that 
each apparent body-ring gives origin to two pairs of minute, 
thread-like feet The mouth is destitute of the powerful jaws 
which are found in the centipedes, the legs are indefinitely 
numerous, and the antenna; are short, and are composed of no 
more than six or seven joints each. 

The European millipedes are all of small size, but an Amer¬ 
ican species is stated to attain a length of more than half a foot. 

A third family has been established for a curious little 
creature called JPauropus, In this the body consists of only 
ten segments, and there are no more than nine pairs of legs. 
The antennas are five-jointed, forked, and provided with jointed 
appendages. There are no trachea*, and respiration is carried 
on by the skin. It is very small, and is found inhabiting 
decayed leaves and damp situations. 





CHAPTER XVII. 


INSECT A. 

Class IV. Insecta. —The true Insects are distinguished 
from the preceding classes of articulate animals by the fact 
that the three divisions of the body , namely , the head , thorax , 
and abdomen, are always distinct from one another; there 
are never more than three pairs of legs in the adult , and these 
are borne upon the thorax ; the abdomen is destitute of loco¬ 
motive appendages. Respiration is effected by means of air- 
tubes or tracheae, and, in most insects, two pairs of wings are 
developed from the back of the second and third segments of 
the thorax. 

The integument in insects is more or less hardened by 
the deposition of chitine in it, and the body is deeply cut into 
segments—hence the name Insect (from the Latin insectus , cut 
into). The head in insects (Fig. 62, a) is composed of several 
segments amalgamated together, and carries a pair of jointed 
feelers or antennce, a pair of eyes, usually compound, and the 
appendages of the mouth. The thorax in insects ( b , c, d) is 
composed of three segments, which are amalgamated together, 
but are generally pretty easily recognized. Each of these 
segments of the thorax carries, in perfect insects, a single 
pair of jointed legs, so that there are three pairs in all. To 
the back of the two hinder segments of the thorax, in most 
insects, there are also attached two pairs of wings. In their 
typical form, the wings are membranous expansions, supported 
by more or less numerous hollow tubes, known as the “ nerv- 
ures.” One or both pairs of wings may be wanting, and 
when all are present the anterior pair may be much modified 
by the deposition of chitine in it. These modifications will 
be treated of in speaking of the orders of insects. The abdo¬ 
men in insects ( e) is properly composed of nine segments, 


INSECT A. 


147 



Fig. 62.— Diagram of the external anatomy of an insect: a Head, carrying the eyes and 
antennae ; b First segment of the thorax, with the first pair of legs; “c Second segment 
of the thorax, with the second pair of legs and the first pair of wings ; d Third seg¬ 
ment of the thorax, with the third pair of legs and the second pair of wings; e Abdo¬ 
men, without limbs, but carrying terminal appendages concerned in reproduction. 


which are usually more or less freely movable upon one an¬ 
other, and which never carry locomotive limbs, as is so com¬ 
monly the case in the Crustacea. The extremity of the abdo¬ 
men is, however, often furnished with appendages which are 
primarily connected with reproduction, but which are often 
converted into weapons of offence and defence. Of this 
nature are the “ ovipositors ” of ichneumons, the stings of 
bees and wasps, and the forceps of the common earwig. 

The organs of the mouth in insects require • a brief consid¬ 
eration, as being in the closest possible relation with their 
habits and mode of life. Two chief types of mouth are recog¬ 
nizable in insects, termed respectively the “ masticatory ” and 
“ suctorial,” according as the mouth is fitted for biting and 
chewing, or simply for imbibing fluids. The masticatory 
mouth is seen in perfection in the beetles, in which the fo]low¬ 
ing organs are present: 1. An upper lip or “ la brum ” at¬ 
tached below the front of the lead. 2. A pair of biting-jaws 














148 


INVERTEBRATE ANIMALS. 


or “ mandibles.” 3. A pair of chewing-jaws or “ maxillae ” 
provided with jointed filaments, called the “ maxillary palpi.” 
4. A lower lip or “labium” which also carries a pair of 
jointed filaments, known as the “ labial palpi.” In the typical 
suctorial mouth, as seen in the butterflies and moths, the fol¬ 
lowing is the arrangement of parts : The upper lip and man¬ 
dibles are quite rudimentary; the maxillae are greatly length¬ 
ened, and form a spiral tube fitted for sucking up the juices of 
flowers; and the labial palpi are much developed, and form 
two hairy cushions between which the trunk can be coiled up 
when not in use. In many insects, the organs of the mouth 

are essentially adapted for suc¬ 
tion, but are also fitted for pierc¬ 
ing solid substances, such as the 
skin of animals or the stems of 
plants. In these the lower lip 
forms a kind of sucking-tube or 
sheath, within which are con¬ 
tained the maxillae and mandi¬ 
bles, which are modified so as 
to form piercing organs or lan¬ 
cets. In the common bee, the 
masticatory and suctorial types 
of mouth are combined. The 
mandibles or biting-jaws are re¬ 
tained, to enable the honeycomb 
to be manufactured, and there 
is also a tubular trunk fitted for 
sucking up the juices of flowers. 
In the butterflies, too, in which 
the mouth of the adult is strict¬ 
ly adapted for suction, the cater¬ 
pillar is furnished with a mas¬ 
ticating mouth, so that it can 
feed upon leaves or other solid 
substances. 

The mouth in the mastica¬ 
ting Insects (Fig. 63, a) leads 
into a membranous and often 
folded cavity, termed the “crop” (b), from which the food 
passes to a second muscular cavity or “gizzard” (c). The 
gizzard is adapted for crushing the food, and often has plates 
or teeth of chitine developed in its walls. It is succeeded 
by the true digestive cavity ( d ), which is termed the “ chy- 






INSECTA. 


149 


lific stomach.” From this there proceeds an intestine (/), 
of variable length, which usually terminates in a chamber (g) 
called the “ cloaca ” (Lat. cloaca , a sink), into which the ducts 
of the reproductive organs open. The commencement of 
the gullet is furnished with glandular appendages, which are 
believed to discharge the functions of salivary glands. Imme¬ 
diately behind the posterior aperture of the stomach are a 
variable number of caecal convoluted tubes (e), which are 
known as the 44 Malpighian vessels,” after their discoverer Mal¬ 
pighi, and which are generally looked upon as representing the 
liver. Close to the cloaca may be other tubes, which are be¬ 
lieved, from their position, to exercise the functions of kid¬ 
neys (A). _ 

The circulation in insects is mainly carried on by a long, 
contractile tube, placed along the back, and termed the 44 dor¬ 
sal vessel.” The blood, collected from the various tissues and 
organs of the body, enters the dorsal vessel from behind, and 
is driven forward to the anterior extremity of the body. Res¬ 
piration is effected by means of air-tubes or trachese, which 
commence at the surface by so many apertures or spiracles, 
and branch repeatedly as they proceed inward through the 
tissues. They have essentially the same structure as in the 
Arachnida , consisting of membranous tubes strengthened by 
means of a spirally-coiled filament of chitine. 

The nervous system in insects, though sometimes some¬ 
what modified, has essentially the regular annulose form of a 
ventral chain of ganglia, traversed in front by the gullet. The 
organs of sense are the eyes and antennae. The eyes are 
usually 44 compound,” and are composed of numerous six-sided 
lenses, united together, and each supplied by a separate ner¬ 
vous filament. As many as eight thousand of these lenses 
have been counted in one of the eyes of the common cock¬ 
chafer, and this number is sometimes greatly exceeded. Be¬ 
sides these compound eyes there are sometimes “simple” 
eyes, identical in structure with the single lenses of the com¬ 
pound eyes; and in rare cases these are the only organs of 
vision. The feelers or antennae, with which all insects are 
furnished, are jointed filaments attached close to the eyes, and 
assuming very different shapes in different insects. They ap¬ 
pear to be certainly organs of touch, but they very probably 
minister to other senses as well, and there is some reason to 
suppose that they are connected with the sense of hearing in 
particular. 

The sexes in insects are distinct, and most of them are 


150 


INVERTEBRATE ANIMALS. 


oviparous. Generally speaking, the young insect is extremely 
different in external character from the adult, and it requires, 
before reaching maturity, to pass through a series of changes 
which collectively constitute what is called the “metamor¬ 
phosis. In some insects, however, there is no proper meta¬ 
morphosis, and in some the changes which take place are not 
so complete and striking as in others. By the absence of met¬ 
amorphosis, or by its completeness when present, insects are 
divided into three convenient, though perhaps not strictly 
natural, sections, as follows: 

Section I. Ametabolic Insects. —The insects belonging to 
this section are said to be “Ametabolic” (Gr. without; 
metdbole, change), because they pass through no metamorpho¬ 
sis. The young, on their escape from the egg, resemble the 
adult in every respect except in size, and they undergo no 
alteration in reaching maturity, except that they grow larger. 
All the insects of this section are destitute of wings in the 
adult state, and they are therefore often called “ Aptera ” 
(Gr. a, without; pteron , a wing). 

Section II. Hemimetcibolic Insects. —In the insects be¬ 
longing to this section (Gr. hemi, half; and metabole , change), 
there is a metamorphosis consisting of three stages, but these 
stages do not differ much from one another in appearance. 
The young, on escaping from the egg, is known as the “ larva,” 
and it is not only much smaller than the adult, but is desti¬ 
tute of wings. After several changes of skin, the larva enters 
into the second stage, when it is termed the “ pupa.” The 
pupa is active and locomotive, and rarely differs much from 
the larva, except that it is bigger, and rudimentary wings 
have now appeared on the back of the thorax. After a cer¬ 
tain period, and after some changes of skin, the wings burst 
from their sheaths, and the pupa is now converted into the 
third and final stage, when it is known as the “ imago ” or 
perfect insect. In all the insects belonging to this section— 
such as grasshoppers, dragon-flies, etc.—the second stage or 
pupa is active and locomotive; and for this reason the meta¬ 
morphosis is said to be “ incomplete.’ 

Section III. Holometdbolic Insects (Gr. holos , entire; and 
metabole , change).—The insects belonging to this section— 
such as butterflies, moths, and beetles—pass through three 
stages, just as do the preceding, but these stages differ from 


INSECTA. 


151 


one another very much in appearance, and the metamorphosis is 
therefore said to be “ complete ” (Fig*. 64). In these insects the 
larva is worm-like, segmented, and usually furnished with loco¬ 
motive feet, which do not correspond with the three pairs proper 
to the adult (see Fig. 71, &), though these are usually present 
as well. The larva is also provided with masticating organs, 



Fig. 64. —Metamorphosis of the Magpie-moth (Phalcena grossulariata). 



and eats voraciously. In this stage of the*metamorpliosis, the 
larvae constitute what are popularly known as “ caterpillars ” 
or “ grubs.” Having remained in this condition for a longer 
or shorter time, and having undergone repeated changes of 
skin, necessitated by its rapid growth, the larva passes into 
the second stage, and becomes a pupa (Fig. 64—see also Fig. 
71). In this stage the insect remains quiescent, unless irri¬ 
tated, and it is very often attached to some foreign object, so 
as to be quite incapable of changing its place. In the case 
of the butterflies and moths, the pupa constitutes what is so 
familiarly known as the “ chrysalis.” The body is protected 
by a chitinous pellicle, and in some cases this is still further 
protected by the dried skin of the larva; while in other cases 
the larva—immediately before entering the pupa stage—spins 


152 


INVERTEBRATE ANIMALS. 


for itself a protective case of silken threads, which surrounds 
the chrysalis, and is known as the “ cocoon.” Having re¬ 
mained for a variable time in this inanimate, quiescent pupa- 
stage, during which rapid changes have been going on in the 
interior of the animal, the insect now frees itself from the en¬ 
velope which obscured it, and appears as the perfect winged 
adult or imago. 


CHAPTER XVIII. 


ORDERS OF INSECTS. 

The known number of insects is so enormous, their forms 
are so various, and their habits and instincts are not only so 
remarkable but have been so fully described, that it were 
hopeless to attempt here to do more than give the briefest 
possible outline of the leading characters which distinguish 
the different orders. The student desirous of further informa¬ 
tion on this head must have recourse to treatises specially de¬ 
voted to entomology. 

Section I. Ametabolic Insects. — Young not passing 
through a metamorphosis , and differing from the adult in 
size only. Perfect insect {imago) destitute of wings; eyes 
simple , sometimes wanting . 

Order I. Anoplura (Gr. anoplos , unarmed; owra, tail). 
—The insects comprised in this order are parasitic upon man 
and other animals, and they are commonly known as Lice. 
They are all very minute in size, destitute of wings in the 
adult state, having a mouth formed for suction, and having 
either two simple eyes or none. 

Order II. Mallophaga (Gr. malios, a fleece; phago , I 
eat).—These are known as “ Bird-lice,” and are all minute 
parasites on different birds. They are distinguished from the 
true lice by not living upon the juices of their host, but upon 
the more delicate and tender appendages of the skin. The 
mouth is, consequently, not suctorial, but fitted for biting. 

Order III. Thysanura (Gr. thusanoi , fringe ; owra, tail). 
—The most familiar members of this order are the “ Spring- 


154 


INVERTEBRATE ANIMALS. 


tails” ( Podurce ), which are commonly found under stones or 
in cellars and such like situations. They are distinguished by 
having the extremity of the abdomen furnished with bristles, 
by the sudden straighteningof which the insect can effect pow¬ 
erful leaps. In many cases the body is covered with delicate 
scales which form beautiful objects under high powers of the 
microscope. 

Section II. Hemimetabolic Insects. — Metamorphosis 
incomplete ; the larva differing from the perfect insect chiefly 
in the absence of wings and in size / pupa usually active , or , 
if quiescent , capable of movement. 

Order IV. Hemiptera (Gr. hemi , half; pteron , wing).— 
In this order the mouth is formed for suction; the eyes are 
compound, but simple eyes are often present in addition. Two 
pairs of wings are always present. 

The Hemiptera live upon the juices of plants or animals, 
which they are enabled to obtain by means of their suctorial 
mouths. All the four wings are generally • present, but the 
condition of these varies in different sections of the order. In 
one group all the four wings are membranous (Fig. 65); but 
in the other the posterior wings and the tips of the anterior 



U 


Fig. 65. Hemiptera. Bean Aphis (Aphis faboi) \ winged male and wingless female. 

wings alone are membranous. The inner portions of the an¬ 
terior wings are hardened by chitine, and they are known as 
“ hemelytra” (Gr. hemi , half; and elutron , a sheath). Among 
the more familiar examples of the Hemiptera are the numeS 
ous species of Plant-lice {Aphides), the Field-bug {Penta- 
toma ), the Boat-fly, the Cochineal insects, and the Cicadas. 

The Cochineal insects are of considerable commercial 1m- 
portance, as the dried and powdered bodies of the female con¬ 
stitute the substance known as Cochineal, from which is ob- 





ORDERS OF INSECTS. 


155 


tained the brilliant, pigment carmine. The male insect is 
winged, and is smaller than the female, which is wingless. 
They live upon different species of Cactus ( OpuntiaJ) and are 
mainly imported from Mexico, Algeria, and the Canary Islands. 

Numerous species of Aphides or Plant-lice (Fig. 65) are 
known, and they are among the greatest pests of the gar¬ 
dener and farmer, as they are extraordinarily prolific, and live 
upon the juices of plants. One of the most curious points 
about the Plant-lice is that they secrete a sweet and sticky 
fluid, which is expelled from the body by two little tubular 
filaments placed near the end of the 
abdomen. Ants are excessively fond 
of this fluid, and hunt after Aphides 
in all directions in order to ob¬ 
tain it; and it is a well-established 
fact that the Plant-lice are actually 
pleased with this, and voluntarily 
yield up the coveted fluid to the 
importunity of the ants. 

Order V. Orthoptera (Gr. or- 
thos , straight; pteron , wing).—The 
mouth in this order is strictly masti¬ 
catory ; there are four wings present 
in most, but the anterior pair is 
smaller than the posterior, and of a 
different texture. The posterior 
wings are membranous, and are fold¬ 
ed lengthwise, like a fan ; the ante¬ 
rior wings are leathery, and consti¬ 
tute cases for the posterior wings 
(elytra). This order includes the 
Crickets ( Achetina ), Grasshoppers 
(Gryllina), Locusts (Locustina), 

Cockroaches ( Blattina , Fig. 66), 
and others. Some of them are 
formed for running, all the legs 
being nearly equal in size; others 
have the first pair of legs greatly developed, and constituting 
powerful organs of prehension; while others, such as the Lo¬ 
custs and Grasshoppers, have the hindmost pair of legs much 
longer than the others, giving them a considerable power of 
leaping. All the Orthoptera are extremely voracious, and 
every one is acquainted with the terrible ravages occasionally 
caused in hot countries by swarms of locusts. 



Fig. 


mon Cockroach (Blatta orienta¬ 
ls), male and female. 











156 


INVERTEBRATE ANIMALS. 


The most destructive species is the Migratory Locust 
(Acrydium migratorium , Fig. 67), which is very abundant in 
Africa, India, and throughout the whole of the East. Owing 
to the rapidity with which they devour every thing they can 
possibly eat, and owing to their enormous numbers, the Lo¬ 
custs are compelled to be constantly on the move, looking for 
“ fresh fields and pastures new.” It is from these migrations 



Fig. 67.—The Migratory Locust [Acrydium migratorium). 


in vast bodies in search of food that the Migratory Locust 
takes its name. When one of these destructive hosts visits 
a district, it only needs a few hours to convert the most fer¬ 
tile country into a howling wilderness. In an incredibly short 
space of time, every green thing on their line of march is 
destroyed, every leaf is stripped from every tree, every blade 
of grass and corn is eaten down, and it is not until the ground 
is utterly bare and brown that the locusts take wing and seek 
out some fresh region to devastate. 

Order VI. Neuroptera (Gr. neuron , nerve; pteron , 
wing).—The mouth in this order is fitted for mastication; the 
wings are four in number, generally nearly equal in size, all 
membranous, and traversed by numerous delicate nervures, 
which interlace so as to form a delicate net-work (Fig. 68). 
The metamorphosis is generally incomplete, but is sometimes 
complete. 

This order includes the well-known and rapacious Dragon¬ 
flies (Libellulidce), the Caddis-flies ( Phryganeidce ), the May¬ 
flies (. Ephemeridce ), the Ant-lion (. Myrmeleo ), the Aphis-lion 
(Fig. 68), Termites, etc. The last of these—namely, the Ter¬ 
mites or white ants—are social insects, living in organized 
communities, and exhibiting many remarkable phenomena. 
They are mostly inhabitants of hot countries, and cause im¬ 
mense mischief by destroying wood-work of all descriptions. 





ORDERS OF INSECTS. 


157 


Though called “ white ants,” it is to be remembered that they 
are not related in any way to the true ants. They build 
mounds of different shapes and sizes, sometimes several feet 
in height, formed of “ particles 
of earth worked into a mate¬ 
rial as hard as stone.” Each 
family of Termites (Fig. 69) 
possesses a king and queen, 
which are always kept together 
closely guarded in a chamber 
placed in the centre of the 
nest. The king (Fig. 69, a) 
and the queen ( b) both origi¬ 
nally possessed wings, but they 
lose these as soon as they 
found a colony. Both are much 
larger than the bulk of the 
community, the queen im¬ 
mensely so, owing to the 
enormous distention of her ab¬ 
domen with eggs. The ordinary Termites are all sterile fe¬ 
males, incapable of laying eggs, and they are divided into two 
distinct sets or “ castes,” both destitute of wings, and differ¬ 
ing in the armature of the head. The one caste includes the 



if' 

Fig. 68.—Neuroptera. Aphis-lion ( Ilemero - 
• biidce), imago, larva, and eggs. 




Fig. 69. —Termites (Termes bellicosm ); a King, before the wings are cast off; 6 Queen, 
with the abdomen distended with eggs; c Worker, d Soldier. 

so-called “ workers,” w T ho perform all the ordinary work of the 
colony, while the “ soldiers ” have greatly-developed jaws, and 
are simply occupied in defending the nest against all enemies. 








158 


INVERTEBRATE ANIMALS. 


Section III. Holometabola. — Metamorphosis complete ; 
the larva , pupa , and imago , differing greatly from one an¬ 
other in external appearance . The larva worm-like , emc? 
jpwjoa quiescent. 

Order VII. Aphaniptera (Gr. aphanos , inconspicuous; 
pteron , wing).—In this order are only the Fleas ( Pulicidce ), in 
which the mouth is suctorial, the metamorphosis is complete, 
and the wings are rudimentary, being represented by four 
minute scales placed on the last two segments of the thorax. 
The larva of the common flea is a footless grub, which in 
about twelve days spins a cocoon for itself, and becomes a 
quiescent pupa, from which the imago emerges in about a 
fortnight more. 

Order VIII. Diptera (Gr. dis, twice; pteron, wing).— 
The insects of this order, as implied by its name, have only a 
single pair of wings—namely, the anterior pair. The poste¬ 
rior witfgs are rudimentary, and are represented by tw 7 o 



Fig. 70.—Diptera. Crane-fly (Tipula oleracea). 


clubbed filaments called “ balancers ” or “ poisers ” (Fig. 70). 
The mouth in the Diptera is suctorial. 





ORDERS OF INSECTS. 


159 


The Diptera constitute one of the largest orders of insects; 
the House-flies and Flesh-flies (Musca), the Gnats ( Culex), the 
Crane-flies ( Tipula ), the Forest-flies ( Hippobosca ), and the 
Gad-flies ( Tabanidce ), constituting good examples. 

Order IX. Lepidoptera (Gr. lepis, scale; pieron, wing). 
—This well-known and most beautiful of all the orders of in¬ 
sects comprises the Butterflies and Moths, the former being 
active by day (diurnal), and the latter mostly toward twilight 
(crepuscular), or at night (nocturnal). In all the Lepidoptera 
the mouth of the adult insect is purely suctorial, and is pro¬ 
vided with a spiral trunk fitted for imbibing the juices of 
flowers. The wings are four in number, and are covered more 
or less completely with modified hairs or scales, which are 
pretty objects under the microscope, and from which the wings 
derive their beautiful colors. The larvae of the Lepidoptera 
(Fig. 71) are generally known as caterpillars. They are worm¬ 
like, provided with masticatory organs fitted for dividing solid 



Fig. 71.—Large white Cabbage-butterfly (Pontia brassicoR). a Larva or caterpillar; b 
Pupa or chrysalis; c Imago or perfect insect. 


substances, possessing false legs in addition to the three pairs 
proper to the adult, and having attached to the under lip a 
tubular organ or spinneret, by which silken threads can be 
manufactured. 

The butterflies or diurnal Lepidoptera are characterized by 
being active during the daytime, by keeping their wings most- 



160 


INVERTEBRATE ANIMALS. 


ly erect when at rest (Fig. 71, c), by haying club-shaped an- 
tenme, and by having a chrysalis (&), which is almost always 
naked and angular, and is generally attached to some solid 
object by silken threads variously disposed. 

The Moths are mostly active during the night-time, when 
they are said to be nocturnal. Many of them, however, are 
“ crepuscular ”—that is to say, they are active during the hours 
of twilight; and a few come out in broad daylight and in the 
brightest sunshine. The pupae, or chrysalides, are never an¬ 
gular, as in the case of the butterflies. 

Apart from the destruction committed by the Caterpillars 
of some of the Lepidoptera , the only members of the order 
which are of importance to man are the various species of 
Bombyx , from which silk is derived. Several species are cul¬ 
tivated for this purpose, but by far the most valuable is the 
common Silk-moth ( Borribyx Mori ), which owes its name to 
the fact that the larva feeds upon the leaves of the common 
Mulberry j^Morus nigra). It is hardly necessary to say that 
raw silk is derived from the “ cocoon,” or silken case in which 
the caterpillar enwraps itself before becoming a chrysalis. 
Most of the raw silk is derived from Franee, Italy, China, and 
the East Indies. 

Order X. Hymexoptera (Gr. humen , membrane; pteron , 
wing).—In this order all the four wings are present, as a rule, 
and they are all membranous in texture, with few nervures 
(Fig. 72). The mouth is always furnished with biting-jaws or 
mandibles, but often is adapted for suction as well. The fe¬ 
males have the extremity of the abdomen furnished with an 
instrument connected with the process of laying eggs (ovi¬ 
positor) ; and in very many cases this becomes the powerful 
defensive weapon known as the sting. The metamorphosis is 
complete. 

The Hymenoptera form a very extensive order, comprising 
the Bees (Apidce), the Wasps ( Vespidce), the Ants ( Formi - 
cidce), the Saw-flies ( Tenthredinidce , Fig. 72), and the Ich¬ 
neumons. The Bees and Wasps are well known as forming 
social communities, though solitary members of both are not 
uncommon. In both groups these organized communities con¬ 
sist of a vast number of undeveloped females, or “ neuters ”— 
the so-called “ workers ”—presided over by a single fertile fe¬ 
male, or “ queen,” or containing several such. The males are 
only produced at certain seasons, and they constitute the so- 
called “ drones ” of a hive of bees. The workers discharge all 

O 


ORDERS OF INSECTS. 


161 


the duties necessary for the preservation of the colony, such 
as procuring food, building the nest, and feeding the young. 
As there is only one set, or “ caste,” of neuters, the duty of 




Fig. 72.—Gooseberry Saw-fly (Tenthredo grossularice), larva, pupa, and imago. 


defending the nest falls to the lot of all the workers, and is 
not delegated to a special class of soldiers. The queen is the 
founder of the colony, and her sole function, after starting the 
community, is to lay eggs. The drones, or males, do no work, 
as a rule, and they either die, or are killed by the workers, as 
soon as the female is fertilized. 

The Ants likewise form communities, consisting of males, 
females, and neuters. The males and females, like those of 
the very different “White Ants,” or Termites, are winged 
(Fig. 73, a ), and are produced in great numbers at particular 
times of the year. They then quit the nest and pair, after 
which the fecundated females lose their wings and form fresh 
societies. The workers (Fig. 73, b) are sometimes all of one 
kind, but they are often divided into two, or even three, 
distinct classes or “castes.” The Ants exhibit many most 
extraordinary and interesting instincts and habits, of which 



162 


INVERTEBRATE ANIMALS. 



Pig. 73.—The Red Ant (Myrmica rufa). a Winged male; & Wingless female. Magnified. 


their custom of “milking” the little Plant-lice has been al¬ 
ready mentioned. Another very singular habit of some Ants 
may be just alluded to—their habit, namely, of capturing the 
pupae of other species of Ants and bringing them up as slaves. 
The relations, however, between the masters and slaves vary 
a good deal in different cases. In the case, for instance, of 
the Russet Ant ( Formica rufescens) the masters are so entire- 
1}’ dependent upon their slaves that they cannot even feed 
themselves, and the only work which they perform unassisted 
is the capturing of fresh slaves. In the Blood-red Ant ( For¬ 
mica sanguined), on the other hand, the slaves are much 
fewer in number, and the masters are much less dependent 
upon their good offices. In all cases, the slaves exhibit the 
greatest devotion to their masters, and are invariably taken 
the greatest care of by their captors. 

Order XI. Strepsiptera (Gr. strepho , 1 twist; pteron , 
wing).—This is an extremely small order of insects, which 
merely requires to be mentioned. It includes only certain 
minute parasites, which are found on bees and other Ily- 
menoptera . The females are destitute of wings or feet, and 
are merely soft, worm-like grubs. The males are active, and 
possess a single pair of large membranous wings. Unlike the 
Diptera , it is the posterior pair of wings which is present, and 
the anterior pair is quite rudimentary, and is only represented 
by curious twisted filaments, from which the name of the 
order is derived. 

Order XII. Coleoptera (Gr. koleos , a sheath; pteron , 
wing).—The twelfth and last order of insects is that of the 
Coleoptera , including the well-known insects familiar to every 



ORDERS OF INSECTS. 


163 


one under the name of “ beetles.” The leading peculiarity of 
the Coleoptera is to be found in the fact, that though all the 
four wings are present, only the posterior pair are mem¬ 
branous, and perform the function of wings. The anterior pair 
of wings are no longer capable of being used in flight, but are 
hardened by the deposition of chitine, and constitute pro- 



Fig. 74.—Coleoptera. The common Cockchafer (Melolontha vulgaris), with the elytra 
closed, and In flight 


tective cases, which cover the hind-wings, and are known as 
“elytra” (Gr. elutron , a sheath). The mouth in all the beetles 
is masticatory, and is furnished with biting and chewing jaws. 

The larvae of the beetles are all worm-like grubs, with 
masticatory mouths, and they all pass through a complete meta¬ 
morphosis, generally requiring a protracted period for its com¬ 
pletion. The known number of different kinds of beetles can¬ 
not be estimated with any certainty, but it is probably little 
short of 50,000 species, and this estimate has been doubled 
by some writers. They are, as a general rule, remarkable for 
their hard, chitinous skin, their glittering, often metallic, 
colors, and their voracious habits, though many of them feed 
upon vegetable matters. 

Of the enormous number of known Beetles, the only one 
which can be said to be of any decided use to man is the so- 
called “ Blister-beetle,” or “ Spanish Fly ” (Cantharis vesica- 
toria). This handsome insect is a native of Southern Europe, 
especially of Italy, Spain, and France, and lives upon the 
leaves of the ash, lilac, elder, and poplar. It is largely col¬ 
lected and exported for medicinal purposes, as it yields one of 
the most generally used and efficient of blisters. 





SUB-KINGDOM V. — MOLLUSCA. 


CHAPTER XIX. 

Sub-kingdom Mollusca. — The Mollusca (Lat. mollis , 
soft), as implied by their scientific name, are mostly soft- 
bodied animals, but their popular name of “ shell-fish ” ex¬ 
presses the fact that their soft body is usually protected by 
an external skeleton or “ shell.” All the Mollusca are fur¬ 
nished with a distinct alimentary canal, which is completely 
shut off from the general cavity of the body (Fig. 75, a). 
There is sometimes no distinct blood-circulatory apparatus; but, 
when there is, its central portion (i. e., the heart) is placed upon 
the dorsal aspect of the body. The chief peculiarity, however, 



Fig. 75.— Diagram of a Mollusk. a Alimentary canal; 7i Heart; / Foot; n Cerebral gan¬ 
glion; n’ Pedal ganglion; n" Parieto-splancknic ganglion. 


of the Mollusca is found in the nature of the nervous system. 
In the lower forms (Fig. 76, 2 d ), the nervous system consists 
essentially of a single ganglionic mass, giving off filaments in 
various directions. In the higher Mollusca (Fig. 75, n), the 
nervous system consists of three scattered ganglia, united to 
one another by nervous cords. One of these ganglia is placed 
above the gullet or oesophagus, and is knowm as the “ supra- 
oesophageal ” or “ cerebral ” ganglion. A second supplies 






MOLLUSCA. 


165 


nerves to the great locomotive organ of most Mollusks, the 
“foot,” and is therefore called the “pedal” ganglion. The 
third is known by the cumbrous name of the “ parieto-splanch- 
nic ” ganglion, because it supplies nervous filaments to the 
w^alls (parietes) of the body, and also to the internal organs 
(splanchna ). In all the higher Mollusks it is this scattered 
condition of the nervous masses which distinguishes them so 
sharply from all other animals. Distinct respiratory organs 
may or may not be present, and they may be adapted for 
breathing air directly or through the medium of water. All 
the higher Mollusca are simple animals, and perpetuate their 
kind by means of the sexes, but many of the lower forms 
have the power of producing colonies by continuous gemma¬ 
tion, much as we have formerly seen in the Hydroid Zoo¬ 
phytes. 

The digestive system in all the Mollusca consists of a 
mouth, gullet, stomach, intestine, and anus, with the excep¬ 
tion of a few forms in which the intestine ends blindly. In 
some the mouth is surrounded by ciliated tentacles ( Polyzoa, 
Fig. 77) ; in others, it is furnished with two long ciliated arms 
(Brachiopoda :); in the bivalves (Lamellibranchiata), it is 
mostly furnished with four membranous processes or “ palpi ” 
(Fig. 80, p) ; in others, it is furnished with a complicated 
toothed organ or “ odontophore ” ( Gasteropoda , Fig. 83, and 
Pteropoda); and lastly, the Cephalopoda, in addition to an 
odontophore, possess horny mandibles, forming a kind of beak, 
very like that of a parrot. 

The blood is colorless, or nearly so. In the lowest class of 
the Mollusca (Polyzoa), the circulation is carried on by means 
of cilia, and there is no distinct heart, nor any definite course 
of the circulating fluid. In the Sea-squirts (Tunicata), there 
is a distinct heart, but the structure of this is very simple, 
consisting of a mere tube, open at both ends, so that the 
course of the circulation is periodically reversed. In the 
higher Mollusca, there is a distinct heart, consisting of two 
chambers, of which one (the auricle) receives the aerated 
blood from the gills, while the other (the ventricle) drives it 
through the body. 

Respiration is very variously effected among the Mollusca. 
In the Polyzoa (Fig. 77) respiration is discharged mainly by 
the crown of ciliated tentacles surrounding the mouth. In the 
sea-squirts (Fig. 78), respiration is effected by a greatly-devel¬ 
oped pharynx, which is perforated by numerous ciliated aper¬ 
tures. In the lamp-shells and their allies (Brachiopoda), the 


166 


INVERTEBRATE ANIMALS. 


long, ciliated arms, which spring from the sides of the mouth, 
seem to be the main agents in respiration. In the bivalve- 
shell-fish, the cuttle-fishes, and most of the univalves, the 
breathing-organs are in the form of gills or branchiae, adapted 
for breathing air dissolved in water. In the remainder of the 
univalves (e. g., snails and slugs), the breathing-organs are 
adapted for breathing air directly, and have the form of an 
air-chamber or pulmonary sac, produced by the folding of a 
portion of the mantle. The air is admitted to the chamber by 
a round opening, situated on the side of the neck, and capable 
of being closed at will. The lining membrane of the chamber 
is richly supplied with blood-vessels, and thus the necessary 
purification of the blood is carried out. 

In accordance with the scattered or rudimentary condition 
of the nervous system, the Mollusca are not characterized by 
acuteness of senses, nor by any great power of locomotion. 
Organs of sight exist in some of the lower and many of the 
higher Mollusca, attaining in the cuttle-fishes (Fig. 89) an ex¬ 
tremely high type of organization. The common bivalve shell¬ 
fish, such as the scallop, possess numerous simple eyes placed 
along the margins of the mantle, but, in many cases, even these 
are absent. Locomotion is very variously effected, but seldom 
with much vigor or activity. The lowest classes of the Mol¬ 
lusca are, in the great majority of instances, fixed when adult. 
The common univalve shell-fish, such as whelks, snails, slugs, 
etc., creep about slowly by means of a flattened disk, devel¬ 
oped on the under surface of the body, and known as the 
“foot.” Other Univalves and many Bivalves can effect short 
leaps by means of the foot, but many of the latter are perma¬ 
nently fixed to solid objects, or buried in the sand. The mi¬ 
nute Mollusca , known as the Pleropoda (Fig. 88), swim freely 
at the surface of the ocean by means of two fins, formed by a 
modification of the foot, and attached to the sides of the head. 
The only Mollusks which enjoy really active powers of loco¬ 
motion are the predacious cuttle-fishes, which swim rapidly by 
means of fins, or by ejecting a jet of water from the cavity of 
the mantle, and which can also creep about by means of the 
“ arms ” placed around the mouth (Fig. 89). 

The last feature in the Mollusca which requires to be men¬ 
tioned is the “ shell.” The shell is not invariably and univer- 
sally present in the Mollusca , many being either destitute of 
a shell altogether, or having one so small that it would not com¬ 
monly be recognized as such. In these cases, as in the com¬ 
mon slugs, the animal is said to be “ naked.” In all the Mol- 


MOLLUSCA. 


167 


lusca which possess a shell, this is secreted by the integument, 
or by what is technically called the mantle, and, in all cases, 
it is composed of carbonate of lime. The methods in which 
the lime is arranged differ in different cases, but all living 
shells have an outer covering of animal matter, which is 
known as the “ epidermis.” In a great many of the higher 
Mollusca , such as the whelks, periwinkles, snails, and others, 
the shell consists of only a single piece, when it is said to be “ uni¬ 
valve.” In many others, such as oysters, mussels, scallops, etc., 
the shell is composed of two pieces, and is then said to be 
“ bivalve.” In a few forms, the shell consists of several pieces, 
and it is then said to be “ multi valve.” The more important 
variations in the shells of the Mollusca will be noticed in 
speaking of the different classes of the sub-kingdom. 

In accordance with the nature of the nervous system, the 
Mollusca are divided into two great divisions, known respec¬ 
tively as the Molluscoida and Mollusca proper. In the Mol- 
luscoida , the nervous system consists of a single ganglion, or 
principal pair of ganglia, and there is either no circulatory 
organ or an imperfect heart. In this division are included the 
three classes of the Sea-mosses ( Polyzoa ), the Sea-squirts ( Tu - 
nicata), and the Lamp-shells and their allies ( Bracliiopoda ). In 
the Mollusca proper , the nervous system consists of three 
principal pairs of ganglia, and there is a w T ell-developed heart, 
consisting of at least two chambers. Under this head come 
all the ordinary forms of shell-fish. 


CHAPTER XX. 


MOLLUSCOIDA. 

Class I. Polyzoa (Gr. polus , many ; zoon , animal.) — 
The members of this class are the lowest of all Mollusca , 
and they are generally known by the popular names of “ Sea- 
mosses ” and “ Sea-mats.” They are invariably compound, 
forming associated growths or colonies, each consisting of a 
number of distinct but similar zobids, produced by gemmation 
from a single primordial individual. The colonies thus pro¬ 
duced are very generally protected by a horny or chitinous 
integument, and they are so like the Hydroid Zoophytes that 
they were long described as such. The only absolute distinc¬ 
tion between the two classes is to be found in the internal 
structure of the zobids of each; but they may be generally 
separated by the fact that the separate cells in a compound 
Hydroid are all united to one another by means of a common 
flesh or coenosarc; whereas in the Polyzoa the separate cells 
composing the colony are merely connected externally, but 
very rarely have any direct communication with each other. 
The separate beings or zobids which collectively constitute the 
colony of an y Polyzo'dn are spoken of as “polypides”—the 
term polypite being only used in connection with the Hydro- 
zoa , and the term polype being similarly restricted to the 
Actinozoa. 

Each polypide in a typical Polyzoon has the following 
structure (Fig. 76, 2): The body of the animal is enclosed in a 
double-walled sac, of wdiich the outer layer is usually chitinous 
or calcareous, and constitutes a “ cell ” in which the zobid is 
contained. This outer layer is known as the “ ectocyst,” to 
distinguish it from the ectoderm of the Goelenterata. The 
cell, thus formed, is lined by a much more delicate membra¬ 
nous layer, which is known as the “ endocyst.” This membra- 


MOLLUSCOIDA. 


109 


nous sac, formed by the endocyst, is pierced by two openings. 
One of these is the mouth, and it is always surrounded by a 
circle or crescent of hollow ciliated processes or tentacles 
(Fig. 76, 2, a). These ciliated tentacles serve partly as respi¬ 
ratory organs, and partly to set up a current of water by 
which floating particles of food are brought to the mouth. 
The mouth and tentacular crown can be partially or com¬ 
pletely pulled into the sac by means of a muscle which is fixed 
to the gullet (2, g ). The mouth leads into a gullet, and that 



Fig. 76. —Morphology of Polyzoa. 1. Fragment of one of the Sea-mats {Flustra truncata ), 
magnified to show the ceils. 2. Diagram of a single polypide of a Polyzoon (after Allman): 
a Mouth surrounded by the ciliated tentacles; b Alimentary canal; c Anus; d Nervous 
ganglion; e Investing sac or “ ectocyst; ” ff Reproductive organs; g Muscle. 3. Bird’s- 
head process. 


again into a stomach, sometimes with a muscular gizzard be¬ 
tween. From the stomach proceeds an intestine of variable 
length, which terminates by a distinct anus at the upper part 
of the sac (2, c). On one side of the gullet, between it and 
the anus, is placed a single nervous ganglion ( d ). Distinct 
reproductive organs (/ f) are also present, and the whole cav¬ 
ity of the sac is filled with fluid. From the above description 
it will be evident that the typical polypide of a Polyzoon 
differs from the polypite of a Ilydrozoon in having 9 distinct 
alimentary canal suspended freely in a body-cavity, and hav¬ 
ing both a mouth and vent, in having a distinct nervous sys¬ 
tem, and in having the reproductive organs contained within 







170 


INVERTEBRATE ANIMALS. 


the body. On the other hand, in the Hydrozoa , there is no 
alimentary canal distinct- from the body-cavity, there is no 
nervous system, and the reproductive organs are in the form 
of external processes of the body-wall. 



Fig. 77.—1. Fragment of Flustra truncata , one of the Sea-mats, natural size. 2. A single 
polypide of Valkeria , magnified, showing the circular crown of tentacles. 3. A polypide 
of Lophoput s crystallinus , a fresh-water Polyzoun, highly magnified, showing the horse¬ 
shoe shaped crown of tentacles: a Tentacular crown; 5 Gullet; c Stomach; d Intestine; 
e Anus; £/Gizzard; k Endocyst; l Ectocyst. 


The foregoing gives the essential structure of the polypide 
of any Polyzoon , but in nature this simplicity is lost. In all 
cases in nature the primitive polypide possesses the power of 
producing fresh zooids by a process of budding; and these 
zotjids remain attached to one another, so that ultimately there 
is produced a compound growth or colony. Further, in almost 
all the Polyzoa , the outer layer of the potypide is more or less 
hardened by the deposition in it of chitine or of carbonate of 
lime. The skeletons thus formed are the parts of the colony 
which are most familiarly known, and in the case of the com¬ 
mon Sea-mats (Fig. 77, 1) they are very well known to sea¬ 
side visitors, and are generally regarded as sea-w r eeds. Exam¬ 
ined in its dead state, such a skeleton only shows a number 
of little horny chambers or cells (Fig. 76, 1), each with a little 
aperture. When alive, however, each of these cells was ten¬ 
anted by a single zo5id or polypide, capable of protruding its 




MOLLUSCOIDA. 


171 


ciliated head from the aperture, and of again retiring within 
it, it alarmed. Hie skeleton is, in some cases, furnished with 
curious organs, which are known as “ bird’s-head processes ” 
(Fig. 76, 3), from their resemblance to the beak of a bird, 
the parts of this beak keep constantly snapping together, 
very much like the little pincer-like organs called “ pedicella- 
riae ” in the sea-urchins and star-fishes; but it is difficult to see 
what service they perform. They continue their movements 
long' after the death of the polypides, and this appears, in some 
cases, at any rate, to be due to a peculiar system of nerves 
known as the “ colonial ” nervous system. In addition, namely, 
to the single ganglion with which each polypide is furnished, it 
has been showm that in many forms the zooids composing the 
colony are united together by a well-developed nervous system, 
and are thus brought into organic connection with one another. 

The vast majority of the Polyzoa are fixed, and thus as¬ 
sume a very plant-like appearance. There is one fresh-water 
species, however (viz., Cristatella ), in which the colony can 
creep about upon a flattened base very like the foot of a slug. 
In this same form, also, alone of all the Polyzoa , there is not 
any outer covering or ectocyst to the polypides. 

The Polyzoa are partly inhabitants of the sea and partly 
of fresh water, and they are thus divided into two groups 
which differ from one another very much in anatomical struc¬ 
ture. In most of the fresh-water Polyzoa the tentacles are 
borne upon a crescentic disk or stage (Fig. 77, 3), so that the 
crown of tentacles assumes the shape of a horseshoe. In 
almost all the marine forms, on the other hand, the tentacles 
(Fig. 77, 2) are simply arranged in a circle. 

All the Polyzoa are hermaphrodite, each polypide being 
furnished with the reproductive organs proper to the two 
sexes. The eggs are simply liberated into the body-cavity, 
where they are fertilized; but it is uncertain how the fertilized 
ova escape into the external medium. Besides true sexual 
reproduction, and besides the power of producing colonies 1 y 
continuous budding, fresh individuals can be produced in many 
cases by a process of discontinuous gemmation. 

Class II. Tunicata (Lat. tunica , a cloak).—The mem¬ 
bers of this class are not uncommonly called Ascidian 31 ol- 
lusks (Gr. askos , a wine-skin) from the resemblance which 
many of them exhibit in shape to a two-necked leather bottle 
(Fig". 78, 2). They are popularly known as “Sea-squirts,” 
from their power of forcibly ejecting water from the orifices 


172 


INVERTEBRATE ANIMALS. 


of the bottle. Their scientific name, again, of Tunicata , is 
derived from the fact that the body is enveloped in a leathery 
elastic integument, which consists of different layers, and which 
takes the place of a shell. The outer covering of the animal 
is of a gristly or leathery consistence, and is known as the 
“ test.” It is remarkable for containing a considerable propor¬ 
tion of a substance apparently identical with cellulose , which 
is one of the most characteristic of all vegetable products. 
The test is lined by a second coat, which is highly muscular, 
and confers upon the animal its power of contracting itself 
and squirting out water. Of the two necks which are placed 
at the anterior end of a simple Ascidian (Fig. 78), one is per- 



c - 


i 


Fig. 78.—Morphology of Tunicata. 1. Diagram of a Tunicary (after Allman): a Oral aper¬ 
ture ; b Atrial aperture; c Respiratory sac, with its rows of ciliated apertures; d Ali¬ 
mentary canal; e Anus; f Cloaca or atx*ium; g Nervous ganglion. 2. A simple 
Ascidian {Cynthia papillosa). 


forated by the aperture of the mouth, while the other serves 
as an excretory aperture. These two apertures are known 
respectively as the “ oral ” and “ atrial ” apertures. 

The oral aperture (a) is usually furnished with a circle of 
small non-retractile tentacles, and opens into a great chamber 
known by various names, but best as the “ respiratory sac.” 
This sac occupies the greater part of the cavity of the body 
(Fig. 78, 1, c), and has its walls perforated by numerous aper¬ 
tures, the sides of which are ciliated. At the bottom of the 
respiratory sac is a second opening (the mouth of some 






MOLLUSCOIDA. 


173 


writers) which leads by a short gullet into a capacious stom¬ 
ach ( d ). From the stomach an intestine is continued to ter¬ 
minate by a distinct anus, which does not communicate direct¬ 
ly with the exterior, but opens into a second great chamber, 
known as the “ cloaca ” or “ atrium ” (e). The cloaca, in turn, 
opens on the exterior by the second, or atrial aperture, in the 
test (b). These two great chambers—namely, the respiratory 
sac and the cloaca—occupy the greater part of the body-cavity, 
and, where their walls come into contact, a free communication 
is established between the two by means of the ciliated aper¬ 
tures already spoken of as perforating the respiratory sac. 
The cilia which fringe these apertures all work toward the 
cloaca, and thus a constant current of water is caused to set 
in by the oral aperture, through the respiratory sac, into the 
cloaca, and out again by the atrial aperture. In this way 
respiration is effected, the walls of the respiratory sac being 
almost made up of blood-vessels. A distinct heart is present 
in all the Tunicata , but it has a very simple structure (1, h ). 
It consists of a simple tube, open at both ends, and not pro¬ 
vided with valves. In consequence of this, the circulation in 
the majority of Tunicaries is periodically reversed, the blood 
being driven for a certain number of contractions in one direc¬ 
tion, and then propelled for a like period in an opposite direc¬ 
tion; so that “the two ends of the heart are alternately 
arterial and venous.” 

The nervous system in the Tunicata consists of a single 
ganglion placed on one side of the oral aperture. 

With one or two exceptions all the Tunicata are hermaph¬ 
rodite, the organs of reproduction being situated in a fold 
of the intestine, and opening into the cloaca. The embryo is 
at first free, and in most swims about by means of a long tail, 
so that it presents considerable resemblance to the tadpole of 
a frog. 

The Tunicata are all marine, but differ a good deal from 
one another in form. In the so-called “ simple ” Ascidians the 
animal has the shape figured above, and is fixed to some solid 
object by one end of the test. In the “ social ” Ascidians the 
organism consists of a number of zooids, produced by con¬ 
tinuous budding, and connected together by a common tube, 
through which the blood circulates. In the so-called “ com¬ 
pound ” Ascidians the tests are fused together into a com¬ 
mon gelatinous mass, in which the individuals are imbedded 
in groups. Some of the Tunicata are oceanic—-that is to 
say, are found floating, or swimming, at the surface of the 


174 


INVERTEBRATE ANIMALS. 


open ocean—and some exhibit the phenomenon of phospho¬ 
rescence. 

In the foregoing description it has been found impossible to convey even 
the most elementary outline of the anatomy of a Tunicate without having 
recourse to technical terms. There still remain a few points of homology 
which should be mentioned. In the foregoing, the so-called “oral aperture” 
of the animal has been regarded as truly the mouth, this being the simplest 
view, and the one held by Prof. Huxley. Upon this view the “ respiratory 
sac,” into which the mouth opens, must be regarded as a greatly-developed 
pharynx (i. e., the upper portion of the alimentary tube). Similarly, on this 
view, the lower aperture of the respiratory sac will have to be regarded as 
the opening of the gullet. By Prof. Allman, again, the respiratory sac is 
looked upon as formed by a great modification of organs corresponding to 
the ciliated tentacles of the Polyzoa , so that the lower aperture of the respira¬ 
tory sac is the true mouth. Lastly, by Prof. Rolleston the respiratory sac is 
looked upon as corresponding to the gills of the Bivalve shell-fish ( Lamelli - 
branchiata ), and the oral and atrial apertures are regarded as corresponding 
to the “respiratory siphons” of these same animals. On this view, the 
lower aperture of the respiratory sac is again looked upon as the true mouth. 
The question cannot be regarded as settled, and Huxley’s view has been 
here adopted merely as being the most readily intelligible to learners. 


Class III. Bkachiopoda. —The members of this class are 
little known to the general public, being all marine, often in¬ 
habiting considerable depths in the sea, and being much more 
abundantly represented by fossil forms than by living ex¬ 
amples. They are often placed with the ordinary Bivalve shell¬ 
fish (. Lamellibranchiata ), in consequence of their universally 
possessing a shell composed of tw^o pieces or valves (Fig. 79), 
but they are really of a much lower organization. In their 
essential structure they show many points of affinity to the 
j Polyzoa, but they are always simple animals, never forming 
colonies, and they always have a bivalve shell. The two pieces 
of which the shell is composed are always placed one in front 
and one behind, so that they are “ ventral ” and “ dorsal,” and 
not “right” and “left” as in the true Bivalves. The two 
valves of the shell are also always slightly, and sometimes 
greatly, different to one another in size, so that the shell is 
said to be “ inequivalve.” The ventral valve is usually the 
largest, and often possesses a prominent curved beak, which 
is generally perforated by an aperture through which there 
passes a muscular stalk by means of which the shell is at¬ 
tached to some solid object. In some cases, however, as in 
Lingula (Fig. 79), the stalk of attachment simply passes be¬ 
tween the valves, and is not transmitted through a distinct 
aperture. In other cases the shell is simply attached by the 
substance of the ventral valve. 


MOLLUSCOIDA. 

The inner surface of the valves of the 
shell is lined by expansions of the integu¬ 
ment, which are called the “mantle-lobes,” 
and which secrete the shell. The digestive 
organs and muscles occupy a small space near 
the apex or “beak” of the shell, which is 
partitioned off by a membranous partition, 
perforated by the aperture of the mouth. The 
remainder of the cavity of the shell is almost 
filled by two long processes, derived from the 
sides of the mouth, fringed with lateral 
branches, and termed the “ arms.” These 
arms are usually closely coiled up, and serve 
to obtain food for the animal. It is from these 
organs that the name of the class is derived 
(Gr. brachion , arm; and podes , feet). The 
arms also serve as respiratory organs, and in 
many forms they are supported on an internal 
calcareous framework or skeleton, sometimes 
called the “ carriage-spring apparatus.” 

The mouth is placed between the bases 
of the arms, and is not furnished with any 
apparatus of teeth. It conducts by a gullet 
into a distinct stomach, surrounded by a well- ^anatina, showing 
developed granular liver. The intestine mav the muscular stalk 
or may not be iurmshed with a distinct anus, is attached, 
but in no case does it open into the body- 
cavity. Within the lobes of the mantle, there is a remarkable 
system of branched tubes, which commence by blind extremi¬ 
ties, and finally communicate with the mantle-cavitv by means 
of certain organs, which were formerly believed to be hearts, 
and are now known as “ pseudo-hearts.” This system of tubes 
appears to be mainly, if not entirely, connected with repro¬ 
duction. A true heart, however, is present in most, if not in 
all, of the Brachiopoda. 

The nervous system consists of a single principal ganglion, 
connected in some cases with others so as to form a collar 
round the commencement of the gullet. In some cases, how¬ 
ever, the nervous system appears to be very rudimentary. 

The sexes appear to be sometimes distinct and sometimes 
united in the same individual. The embryo, in some cases, at 
any rate, is locomotive, moving from place to place by means 
of the ciliated arms or by ventral spines. 



CHAPTER XXI. 


MOLLFSCA PKOPEJJ. 


The higher Mollusca or Mollusca proper comprise those 
members of the sub-kingdom in which the nervous system 
consists of three principal pairs of ganglia; and there is 
always a well-developed heart , consisting of at least two 
chambers. 

In this division are included the following classes: 

1 . Lamellibranchiata , without a distinct head. 


2 . Gasteropoda , 

3. Pteropoda, 

4. Cephalopoda , 


with a distinct head and a masticatory 
apparatus or “ odontophore.” 


Class I. Lamellibranchiata. —These are well known as 
bivalve shell-fish, such as mussels, oysters, scallops, etc., and 
they are all either marine or inhabitants of fresh water. They 
are distinguished from the other Mollusks by having no dis¬ 
tinct head, and by having the body more or less completely 
protected by a bivalve-shell composed of two pieces. They 
are called Lamellibranchiata (Lat. lamella , a plate ; Gr. brag- 
chia , gill), from the fact that the organs of respiration are in 
the form of leaf-like gills or branchi®, two of which are placed 
at each side of the body, constituting what is known in the 
oyster as the “ beard.” The body of the Lamellibranchiata 
is more or less completely enclosed in an expansion of the 
integument which constitutes the “ mantle,” and which is 
divided into two halves or “ lobes,” which are placed on the 
sides of the animal, and secrete the shell. The shell, there¬ 
fore, of the true bivalves is composed of two valves, which 
are “ right ” and “ left,” and not “ dorsal ” and “ ventral,” as 
in the JBrachiopoda. Moreover, the valves of the shell are 
usually of the same size, so that the shell is “ equivalve,” and. 


MOLLUSCA PROPER. 


177 

lastly, the shell is more developed on one side than the other, 
so as to become “inequilateral” (Fig. 81, 2). The lobes of 
the mantle are sometimes 
quite free ; but, at other times, 
they are more or less united 
to each other, and leave only 
two openings. Through one 
of these openings (the ante¬ 
rior) the “ foot ” is protruded 
(Fig. 80, f ); and through 
the other pass the respiratory 
tubes or “siphons” (s). The 
foot in the bivalves is a mus¬ 
cular organ developed upon 
the lower surface of the body, 
but not forming a creeping 
flattened disk, as in the ordi¬ 
nary univalves. In many 
cases, it is quite rudimentary ; 
and even when it is employed 
in locomotion it is usually 
small. Most generally, it is 
hatchet-shaped or pointed 
(Fig. 80, /*), and serves to 
enable the animal to make 
short leaps. In many cases, 
as in the common mussels, 
the foot is subsidiary to a 
special gland, which secretes 
a viscous fluid, which hardens 
rapidly on exposure to the 
air. This fluid is moulded 
by the foot into silky threads 
(the so-called “byssus”), by 
means of which the shell is 
firmly fixed to some solid 
object. Besides the muscular 
foot, other muscles are pres¬ 
ent as well in the Lamelli - 
branchiata. Of these, the 
most important are the 
muscles which close the shell, 
and are called the “ adduc¬ 
tor” muscles. In one group of the bivalves (Fig. 81, 3), there 



Fig. 80. —Anatomy of a Bivalve Mollusk. My a 
arenaria (after Woodward). The left 
valve and mantle-lobe, and half the siphons 
are removed, s s Respiratory siphons, thi 
arrows indicating the direction of the cur¬ 
rents ; a a' Adductor muscles; b Gills; h 
Heart; o Mouth, surrounded by (p) labial 
palpi;/Foot: ttAnus; m Cut edge of the 
mantle. 








178 


INVERTEBRATE ANIMALS. 


is only one adductor muscle, but ordinarily there are two (Fig. 
81, 2). These muscles leave distinct scars or “ muscular im¬ 
pressions ” in the dead shell, so that it is easy to determine 
how many were present in any given shell. The margin of 
the mantle, too, is muscular, and leaves upon the shell a dis¬ 
tinct line where it was attached, this being known as the 
“pallial line” (Lat. pallium, a mantle), as shown in Fig. 81. 

As regards the shell of the bivalves, the following are the 
chief points to be noticed. Each valve of the shell (Fig. 81) 
is to be regarded as essentially a hollow cone, the apex of 
which is turned more or less to one side. The apex of the 
valve is known as the “ umbo ” or “ beak,” and is turned tow¬ 
ard the mouth of the animal. Consequently, the side of the 



Fig. 81.—Sheila of Lamellibranchiata. 1. Cyclas amrdca, a shell with two adductor 
muscles, and an “entire” mantle-margin. 2. Tapes pullastra , a shell with two adduc¬ 
tors, and an indented pallial line. 8. Pema ephippium, a shell with one adductor 
muscle: a Pallial line; b Scars left by the adductors; c Siphonal impression. 


shell toward which the beaks are turned is known as the 
“ anterior ” side, and it is usually much shorter than the oppo¬ 
site or “ posterior ” side. The side of the shell at wdiich the 
beaks are situated is known as the “ dorsal ” margin ; and here 
the valves are united to one another for a longer or shorter 
distance along a line which is known as the “ hinge-line.” 
The union between the valves is usually effected by means of 
interlocking parts or “ teeth,” and there is often a band of 
horny fibres passing between the two valves just behind the 
bsaks. In many cases, there is also a series of horny fibres 
placed perpendicularly between the beaks, so as to be com¬ 
pressed when the shell is shut. By the elasticity of these, 
and of the external ligament, when present, the valves of the 
shell are opened, without any effort of the animal, simply by 
relaxing the adductor muscles. The valves are shut again by 
the contraction of the adductor muscle or muscles. 







MOLLUSCA PROPER. 


179 

As already said, the margin of the mantle leaves on the 
shell a distinct impression—the “ pallial line ”—and, by inspec¬ 
tion of this, important conclusions can be drawn in any given 
case as to the mode and life of the animal. In certain shells, 
namely, the pallial line (Fig. 81,1) is unbroken or “ entire,” and 
in these the mantle-lobes were either quite free, or if attached 
to one another and drawn out into respiratory tubes, these 
were not furnished with special muscles by which the tubes 
could be retracted within the shell. In other bivalves, on the 
other hand (Fig. 81, 2), the pallial line is indented to a greater 
or less extent, showing that the mantle-lobes were more or 
less united to one another, and were drawn out into long 
respiratory tubes or siph'ons, which were furnished with spe¬ 
cial muscles by which they could be withdrawn within the shell. 
This difference expresses a real distinction among the bivalves, 
due to their mode of life. In all alike, the respiratory organs 
are in the form of membranous leaf-like gills, of which there 
are generally two on each side of the body. The gills are- 
composed generally of tubular rods (Fig. 80, b) richly supplied 
with blood-vessels, and covered with vibrating cilia. For the 
proper maintenance of respiration, however, it is necessary 
that the gills should be constantly supplied with fresh water. 
In those bivalves in which the animal is free and the mantle- 
lobes not attached to one another, this is effected without any 
special mechanism. In those forms, however, in which the 
animal lives buried in the mud and sand, and the mantle-lobes 
are more or less completely united, there are two orifices, one 
of which admits fresh water, while the effete water is got rid 
of through the other. These orifices, in the shells just spoken 
of, are extended into two long tubes which are known as the 
“respiratory siphons.” The water passes in by one siphon, 
is swept over the surface of the gills, and then reaches the 
mouth (Fig. 80, s s), when it is returned in the opposite 
direction to escape by the other siphon. The same current of 
water, therefore, both carries oxygen to the gills, and serves 
to convey food to the mouth. The two siphons may be quite 
distinct from one another, but they are very often united 
together so as to look like a single tube (Fig. 80). They are 
often very small, and then they leave no traces of their ex¬ 
istence in the dead shell; but, when they are very long, they 
are furnished with muscles to retract them within the shell, 
and it is the scar left by these muscles which causes the pallial 
line to be indented. This indentation, therefore, as seen in 
the dead shell, is an indication that the animal possessed long 


180 


INVERTEBRATE ANIMALS. 


retractile respiratory siphons, and lived, therefore, most prob¬ 
ably imbedded in sand or mud. 

There is always a distinct heart, composed of two or three 
chambers, and in all cases acting as a mere arterial heart. 
That is to say, the heart propels the aerated blood derived 
from the gills through the body, and has nothing to do with 
the propulsion of the non-aerated or venous blood through the 
gills. There is never any distinct head in any of the Bivalves, 
and for this reason they are sometimes called the “ headless ” 
(<acephalous ) Mollusks. The mouth is simply placed at the 
anterior end of the body, and is never furnished -with teeth, 
though usually provided with membranous processes or 
“ palpi” (Fig. 80, p). The mouth opens into a gullet which 
conducts to a stomach. The intestine is convoluted, and usu¬ 
ally perforates the ventricle of the heart, ultimately terminating 
in a distinct anus, which is always placed near the respiratory 
aperture. A large and well-developed liver is also present. 

The nervous system has its normal form of three principal 
masses—the cerebral, the pedal, and the parieto-splanchnic 
ganglia. 

The majorit} T of the bivalve Mollusks have the sexes dis¬ 
tinct, but they are sometimes united in the same individual. 
The young are hatched before they leave the parent, and, 
when first liberated, are ciliated and free-swimming. 

The habits of the Lamellibranchiata are very various. 
Some, such as the Scallops (Pecten), habitually lie on one 
side, the lower valve being the deepest, and the foot rudimen¬ 
tary or wanting. Others are fixed to the bottom of the sea 
by the substance of one of the valves. Others, such as the 
common Mussel, are moored to some foreign object by a tuft 
of silky fibres, constituting a “ byssus.” Many, such as the 
Gapers (Mya) and Razor-shells ( Solen ), spend their existence 
sunk in the sand of the sea-shore or the mud of estuaries. 
Others, such as the Pholades , bore holes in rock or wood, in 
which they live. Finally, many are permanently free and 
locomotive. 

Class II. Gasteropoda (Gr. gaster , belly ; podes, feet).— 
This class includes an enormous number of Mollusks, such as the 
land-snails, sea-snails, whelks, limpets, slugs, sea-lemons, etc., 
which agree in many fundamental characters, but nevertheless 
present many striking differences. From the very common 
occurrence of a shell composed of a single piece, the Gastero * 
poda are often spoken of in a general way as the “ univalve ” 


MOLLUSCA PROPER. 


181 


Mollusks. In many, however, there is either no shell at all, or 
one so small that it would not generally be recognized as such; 
and in a few the shell is composed of several pieces (“ multi¬ 
valve ”). In none, however, is the shell composed of two 
pieces or “ bivalve.” The great majority of the Gasteropoda 
are further distinguished by the great development of the 
foot, which constitutes a broad, flattened disk upon which they 
creep about, as may readily be observed in the common slugs. 
Some, however, have the foot much modified and adapted for 
swimming. In many cases, also, the foot carries behind a 
horny or shelly plate which is known as the “ operculum ” 
(Fig. 82, o), and which serves to close the shell when the 
animal is withdrawn within it. 



Fig. 82.—Gasteropoda. Ampullaria mnalfculata, one of the Apple-shells: 
o Operculum; $ Respiratory siphon. 


The head in most of the Gasteropoda , unlike the Bivalves, 
is very distinctly marked out, and carries two long feelers, and 
two eyes, often placed upon stalks (Fig. 85). The mouth, 
also, differs from that of the Bivalves in being furnished with a 
singular apparatus of teeth, constituting what is known as 
the “ odontophore ” (Fig. 82), or “ lingual ribbon.” This con¬ 
sists essentially of a number of siliceous teeth, of different 
shapes in different species, supported upon a kind of strap which 
can be made to work backward and forward over a cartila¬ 
ginous cushion, thus acting like a chain-saw. In addition to 
the odontophore there are sometimes horny jaws as well. The 
mouth leads by a gullet into a distinct stomach, which some¬ 
times is provided with calcareous plates for grinding down 
the food. The intestine is long, and always terminates in a 
distinct anal aperture. Distinct salivary glands are usually 
present, and the liver is well developed. 


182 


INVERTEBRATE ANIMALS. 


A distinct heart is almost always present, and consists of 
two chambers, an auricle and a ventricle. Respiration is very 
variously effected—one great division being constructed to 
breathe air by means of water, while in another section the 
respiration is aerial. In the former of these—often spoken of 
as the “ branchiate ” Gasteropods—respiration may be carried 
on in three ways : Firstly, there may be no special breathing- 
organ, the blood being simply exposed to 
the action of the water, as it circulates 
through the thin walls of the mantle-cavity. 
Secondly, the breathing-organs may be in 
the form of outward processes of the skin, 
exposed to view on the back or sides of the 
animal (Fig. 85). Thirdly, the breathing- 
organs are in the form of plume-like gills, 
contained in a more or less complete cham¬ 
ber, formed by a folding of the mantle. In 
many members of this group the water ob¬ 
tains access to the gill-chamber by means of 
Fig. 83.—Portion of the a tubular prolongation or folding of the 
commonwhSk^mag- mantle, forming a siphon (Fig. 82, s), and 
^ after Wood ‘ often the effete water is expelled by another 
tube which is similarly constructed. In the 
second great section—often called the “ pulmonate ” Gaste¬ 
ropods—respiration is effected by a pulmonary chamber or lung, 
formed by a folding of a mantle, and having air admitted to 
it by a distinct aperture. 

The sexes in the Gasteropoda are mostly distinct, but they 
are sometimes united in the same individual. The young, 
when first hatched, are always provided with an embryonic 
shell, which may be entirely lost in the adult, or may simply 
become concealed by a fold of the mantle. In the water- 
breathing forms the young is protected by a small nautilus¬ 
shaped shell, within which it can entirely withdraw. It is en¬ 
abled to swim about freely by means of two ciliated lobes spring¬ 
ing from the sides of the head, and in this stage it is very 
like the permanent adult condition of the Pteropoda (Fig. 88). 

As regards the. shell of the Gasteropoda , the following 
points may be noticed: The shell is composed either of a 
single piece (univalve), or of a number of plates placed one 
behind the other (multivalve). 

The univalve shell is to be looked upon as essentially a 
hollow cone, the apex of which is placed a little on one side. 
In the simplest forms, as in the Limpets, the conical shell is 






MOLLUSCA PROrER. 


1S3 


retained throughout life without any alteration. In the great 
majority of cases, however, the cone" is considerably elongated 
so as to form a tube, which may retain this shape (as in the 
“tooth-shell”), but which is usually coiled up into a spiral 
The 44 spiral univalve” may, in fact, be regarded as the typicai 



Fig. 84. —Gasteropoda, a Shell of the Turritella communis . showing a round mouth; 
b Shell of the common whelk (Buccinum undatum ), showing the mouth notched for 
a respiratory siphon. 

form of the shell in the Gasteropoda (Fig. 84). The coils of 
the spiral are termed the 44 whorls,” and are usually more or 
less amalgamated on one side. In most cases, too, the whorls 
are wound obliquely round a central axis or pillar, increasing 
gradually in size to the mouth. The last whorl is the largest, 
and is termed the 44 body-whorl.” The mouth of the shell in 
many forms is unbrokenly round or 44 entire ” (Fig. 84, a), and 
it is found that most of these shells subsist upon vegetable 
food, as, for instance, the common periwinkles. In others, 
again (Fig. 84, £), the mouth of the shell is notched or is pro¬ 
duced into a canal, as in the common W'helk, and it is found 
that these live upon animal food, or are 44 carnivorous.” There 
may be more than one of these canals or tubes, but they do 
not necessarily indicate the nature of the food, as their func¬ 
tion is to protect the respiratory siphons. 

The Gasteropoda are divided into a good many groups, 
of which the more important may be briefly noticed, the fore¬ 
going applying chiefly to the ordinary forms, which, therefore, 
need no further description. The remaining members of the 


184 


INVERTEBRATE ANIMALS. 


water-breathing Gasteropods are divided into two sections, 
differing a good deal from the typical forms of the class in 
many respects. 

As examples of the first of these may be taken the sea- 
slugs and sea-lemons ( Nudibranchiata ), specimens of which 
may at any time be found creeping about on sea-weeds, or at¬ 
tached to the under surface of stones at low water. These 
slug-like animals (Fig. 85) are wholly destitute of a shell when 

fully grown, but possess an em¬ 
bryonic shell when young. When 
there are any distinct respiratory 
organs, these are in the form of 
gills, placed, without any protec¬ 
tion, upon the back or sides of 
the body. The head is furnished 
with tentacles, which do not ap¬ 
pear to be used as organs of touch, 
but are more probably connected with the sense of smell; and 
behind the tentacles are generally two eyes. The nervous 
system is extremely well developed, and would lead to the be¬ 
lief that the Sea-slugs are among the highest of the Gastero¬ 
poda. Locomotion is effected, as in the true Slugs, by creep¬ 
ing about on the flattened foot. 

The last remaining group of the “ branchiate ” Gasteropods 
is that of the Heteropoda (Fig. 86), comprising a number of 
curious forms which are found swimming at the surface of the 



Fig. 85.—Nudibranchiata. Doris John 
8to)ii, one of the Sea-lemons. 



open sea, instead of creeping about at the bottom of the sea. 
In order to adapt them for this mode of life, the foot, instead 
of forming a creeping disk, is modified to form a compressed 
fin (/*). The Heteropoda are to be regarded as the most 




MOLLUSCA TROPER. 


185 


highly organized of all the Gasteropoda , at the same time that 
they are not the most typical members of the class. Some of 
them can retire completely within their shells, but others have 
large bodies, and the shell is either small or entirely absent. 
In Carinaria, which may be taken as a good example of the 
group, there is a little limpet-shaped shell protecting the 
gills ( b) and heart. The animal swims, back downward, by 
means of a vertically-flattened ventral fin (/), on one side of 
which is a little sucking-disk (d), by which the animal can ad¬ 
here at pleasure to floating sea-weed. Carinaria is found in the 
Mediterranean and other warm seas, and is so transparent that 
the course of the intestine can be seen along its whole length. 

The last group of the class is that of the “ air-breathing ” 
Gasteropods, so well known as Land-snails, Pond-snails, and 
Slugs (Fig. 87). All the members of this group are formed 
to breathe air directly, instead of through the medium of 
water, and they, therefore, never possess gills or branchiae. 



Fig. 87.— Limax Sowerbyi, one of the slugs (after Woodward). 


In place of these they have a pulmonary chamber or lung, 
formed by a folding of the mantle, and having air admitted to 
it by a round hole on the right side of the neck, which can be 
opened and closed at will. Though thus adapted for breath¬ 
ing air directly, many of the members of this group can only 
live in damp or moist places, while others habitually live in 
fresh water. The common Pond-snails are examples of these 
last. The condition of the shell varies much. Some, such as 
the common Land-snails, have a well-developed shell within 
which the animal can completely withdraw itself for protec¬ 
tion. Others, such as the common Slugs (Fig. 87), have a 
rudimentary shell which is completely concealed within the 
mantle. Others are entirely destitute of a shell. They all 
agree with the typical Gasteropods in creeping about on a 
broad, flattened foot. 

Class III. Pteropoda (Gr. pteron, wing; podes, feet).— 



186 


INVERTEBRATE ANIMALS. 


This class is a very small one, and includes a number of minute 
oceanic Mollusks, which are found swimming near the sur¬ 
face in the open ocean, far from land, and often in enormous 
numbers. The organs of locomotion are two wing-like fins 
(Fig. 88) attached to the sides of the head, and formed by a 



Fig. 88.—Pteropoda. a Cleodora pyrcimidata ; & Cuvieria columneUa. 

(After Woodward.) 

modification of a portion of the foot. The body is usually pro¬ 
tected by a symmetrical glassy shell (Fig. 88), consisting of 
two plates united along their edges, or in other cases forming 
a spiral. In some, however, there is no shell, and the body is 
quite naked. The head is rudimentary, and bears the mouth, 
which is furnished with an odontophore. The heart consists 
of an auricle and ventricle, and the respiratory organs are 
extremely rudimentary. The sexes are united in the same 
individual in all the Pteropoda. 

The Pteropoda occur, as already said, in the open ocean, 
and they are found in all seas from the tropics to within the 
arctic circle, sometimes in such numbers as to discolor the 
water for many miles. Minute as they are, they constitute in 
high latitudes one of the staple articles of diet of the whale, 
and they themselves in turn are probably carnivorous, feed¬ 
ing upon small Crustaceans and other diminutive creatures. 
Though all the living forms are small, geology leads us to be¬ 
lieve that formerly there existed comparatively gigantic forms, 
which appear to be truly referable to this class. 



CHAPTER XXII. 


CEPHALOPODA. 


Class IV. Cephalopoda. —The last and highest class of 
the Mollusca is that of the Cephalopoda, comprising the 
Cuttle-fishes, Calamaries, Squids, and the Pearly Nautilus. 
They are all inhabitants of the sea, 
and are all carnivorous; and they are 
possessed of considerable powers 
of locomotion. At the bottom of 
the sea they can walk about, head 
downward, by means of the arms 
(Fig. 89), which surround the 
mouth, which are usually provided 
with numerous suckers, and which 
are really produced by a splitting 
up of the margin of the foot. It is 
from the presence of these arms 
that the class derives its name (Gr. 
kephale, head; and podes, feet). The 
Cuttle-fishes can also swim rapid¬ 
ly, either by means of expansions 
of the skin constituting fins, or by 
the forcible expulsion of water 
from the cavity of the mantle, the 
reaction of which causes the animal 
to move in the opposite direction. 

The majority of the living Cephalo- Fk . m ^ pio!a AtMiea , » M of 
pods are naked, possessing only an the Cuttle-fishes (after Wood- 

internal skeleton, and this often a war ' 

rudimentary one; but the Argonaut (Paper Nautilus) and the 
Pearly Nautilus are protected by an external shell, though 
the nature of this is extremely different in the two forms. 



188 


INVERTEBRATE ANIMALS. 


The body in the Cephalopoda is symmetrical, and is en 
closed in an integument which may be regarded as a modificaN 
tion of the mantle of the other Mollusca. Ordinarily there is 
a tolerably distinct division of the body into an anterior por¬ 
tion, carrying the head, and a posterior portion, in which 
the internal organs are enclosed. The head (Fig. 89) is 
very distinct, bearing a pair of large globular eyes, and 
having the mouth in its centre. The mouth is surrounded 
by a circle of eight, ten, or more, long muscular processes, 
or arms, which are generally provided with rows of suckers. 
Each sucker consists of a cup-shaped cavity, the muscular 
fibres of which converge to the centre, where there is a 
little muscular eminence. When the sucker is applied to any 
surface, the contraction of the radiating muscular fibres de¬ 
presses the central eminence so as to produce a vacuum below 
it, and in this way each sucker acts most efficiently as an ad¬ 
hesive organ. The whole of this complex mechanism of suckers 
is completely under the control of the animal, and the ir¬ 
ritability of the suckers is retained even for days after death. 
In most of the Cuttle-fishes ( Octopoda) there are only eight 
arms, and these are nearly similar to one another. In others, 
however (Fig. 89), there are ten processes round the mouth, 
of which eight are like each other, and constitute the true 
arms, while two—called tentacles—are much longer than the 
others, and bear suckers only toward their extremities, which 
are enlarged and club-shaped. The Paper Nautilus (Fig. 90) 
has two of the arms webbed at their extremities and secreting 
a shell; and the Pearly Nautilus, alone of all living Cephalo¬ 
poda , has numerous arms, more than ten in number, and 
destitute of suckers. 

The mouth leads into a cavity containing two powerful 
horny or partially calcareous jaws working vertically, very 
like the beak of a bird, together with an “ odontophore ” or 
“ tongue,” the hinder part of which is furnished with recurved 
spines. This cavity leads by a gullet, furnished with salivary 
glands, into a stomach, from which an intestine is continued 
to terminate by a distinct anus, which opens on the ventral 
surface at the base of the so-called “ funnel.” The funnel is a 
muscular tube placed on the under surface of the head, and 
communicating on the one hand with the external medium, 
and on the other with the cavity of the mantle. In the JVau- 
tilus alone it is simply formed of two muscular lobes, which 
are in apposition, but are not united together so as to form a 
tube. In many cases there is also a special gland, known as 


CEPHALOPODA. 


189 


the “ ink-bag,” for the secretion of an inky fluid, which the 
animal discharges into the water, so as to enable it to escape 
when menaced or pursued. The duct of the ink-bag opens at 
the base of the funnel near the anus, but the Pearly Nautilus 
and the allied fossil forms are without this means of defence, 
which the presence of an external shell renders unnecessary. 

The respiratory organs are in the form of plume-like gills, 
placed on the sides of the body in a branchial chamber, which 
opens in front on the under surface of the body. In almost 
all the living Cephalopoda there are only two gills, one on 
each side, and hence this section is known as that of the 
“ pibranchiata.” In the Pearly Nautilus alone there are four 
gills, two on each side, hence the name of “ Tetrabranchiata ” 
applied to the order of which this is the only living represent¬ 
ative. In the Cuttle-fishes, at the base of each gill is a special 
contractile cavity, called a “ branchial heart,” by which the 
venous blood, returned from the body, is driven through the 
gills. In addition to these branchial hearts there is a true 
arterial heart, by which the aerated blood received from the 
gills is driven through the body. The admission of water to 
the branchiae is effected by the expansion of the mantle, which 
allows the entrance of the outer water into the mantle-cavity. 
The mantle then contracts, and the water is forcibly expelled 
through the funnel, which is often furnished with a valve, al¬ 
lowing the passage of water outward, but preventing its en¬ 
trance inward. By a repetition of this process both respira¬ 
tion and locomotion are simultaneously effected, for the jets 
of water expelled from the funnel by their reaction drive the 
animal in the opposite direction. In this case, therefore, as in 
many others, the more active the animal is, the more perfectly 
is the respiratory process carried on. 

The nervous system is formed upon essentially the same 
plan as in the other Mollusca , but the cerebral ganglia are 
protected by a cartilage, which is to be regarded as a rudimen¬ 
tary skull. This structure, therefore, is a decided approach to 
the Vertebrate type of organization. 

The sexes in all the Cephalopoda are in different individ¬ 
uals, and the reproductive process in the Cuttle-fishes is at¬ 
tended with some singular phenomena. The most remarkable 
point in this connection is the modification of one of the arms 
of the male Cuttle-fishes, for the purpose of conveying the 
male element to the female. The details of the modification 
vary in different species of Cuttle-fish. 

In some species one arm is simply so modified as to be 


190 


INVERTEBRATE ANIMALS. 


able to transmit the sperm-cells to the female, but it remains 
permanently attached to the animal. In the Paper Nautilus 
{Argonaut) the process goes still further. The female of this 
species (Fig. 90) attains a considerable size, and is protected 
by an external shell. The male is not more than an inch in 
length, is devoid of a shell, and has its third left arm meta¬ 
morphosed. This arm is developed in a cyst, and is ultimately 
detached from the body, and deposited by the male within 
the mantle-cavity of the female. When first discovered in this 
position, it was described as a worm living parasitically on 
the Argonaut, under the name of “ Hectocotylus ” (Gr. heJcaton ,, 
a hundred; and kotulos , a cup), from the suckers, or cups, with 
which it was furnished. Subsequently it was described as the 
entire male Argonaut; and it is only recently that it has been 
proved to be nothing more than one of the arms of the male, 
detached for the purpose of conveying the sperm-cells to the 
female. 

The shell of the Cephalopoda is sometimes external, some¬ 
times internal. The internal skeleton is seen in the various 
Cuttle-fishes, in which it is known as the “ cuttle-bone ” or 
“ pen.” It may be either horny or calcareous, and it is some¬ 
times complicated by the addition of a chambered portion. 
The only living Ceplialopods which are provided with an ex¬ 
ternal shell are the Paper Nautilus (Argonauta) and the 
Pearly Nautilus {Nautilus pompilius ); but not only is the 
structure of the animal different in each of these, but the 
nature of the shell itself is entirely different. The shell of 
the Argonaut (Fig. 90) is coiled into a spiral, but it is not di¬ 
vided into chambers, and it is secreted by the w'ebbed extrem¬ 
ities of two of the dorsal arms of the female. These arms 
are bent backward, so as to allow the animal to live in the 
shell; but there is no organic connection between the shell and 
the body of the animal. The shell of the Pearly Nautilus, on 
the other hand, is secreted by the mantle, and is organically 
connected to the animal. It is coiled into a spiral (Fig. 91), 
but it differs from the shell of the Argonaut in being divided 
into a series of chambers by means of shelly partitions, which 
are connected together by a tube or “ siphuncle,” the animal 
itself living in the last and largest chamber only of the shell. 

The Cephalopoda are divided into two extremely dis¬ 
tinct and natural orders, termed respectively Dibranchiata and 
Tetrabranchiata , according as they have two or four gills or 
branchiae;. 

The Dibranehiata comprise the Cuttle-fishes, Squids, Cala- 


CEPHALOPODA. 


191 


maries, and Paper Nautilus, and they are characterized by 
being almost invariably destitute of any external shell; by 
never having more than eight or ten arms, which are always 
furnished with suckers; by having only two gills, which are 
provided with “ branchial hearts; ” by the possession of an 
u ink-bag ; ” and by the fact that the “ funnel ” forms a com¬ 
plete tube. They are divided into two sections— Octopoda 
and Decapoda —according as they have only eight arms, or 
eight arms with two additional longer processes or “tentacles ” 
(Fig. 89). Among the Octopoda are the Paper Nautilus and 
the Poulpes ( Octopus). The Paper Nautilus is found in the 
warmer seas of various parts of the world, generally floating 
at the surface. The two sexes differ, as already said, greatly 
in external appearance. The female (Fig. 90) inhabits a beau- 



Fig. W.—Argonauta, argo , the Paper Nautilus, female. The animal is represented in its 
shell, but the webbed dorsal arms are separated from the shell which they secrete, and 
which they ox-dinarily embrace. 


tiful one-chambered shell, which is secreted by the webbed ex¬ 
tremities of two of the dorsal arms. The shell is not in any 
way attached to the body of the animal, but the webbed arms 
are turned backward, and the animal sits in the shell with the 


192 


INVERTEBRATE ANIMALS. . 


funnel turned toward the keel. It swims by the jets of water 
emitted from the funnel, and crawls upon the sea-bottom, head 
downward, carrying its shell on its back. The male Argonaut 
is only about an inch in length, has no shell, and has all its 
arms alike, except the one which is metamorphosed into the 
“ hectocotylus.” The Poulpes ( Octopi ) are universally dis¬ 
tributed in the seas of both temperate and tropical regions. 
They are the “ polypi ” of Homer and Aristotle, and are vo¬ 
racious animals inhabiting rocky shores. 

The Decapoda are chiefly found in the open sea, often in 
enormous numbers, and the best known are the Calamaries 
and Squids. The body is elongated, and is always furnished 
with lateral fins, with which they swim actively. The shell is 
internal, and differs considerably in different members of the 
group. To this section of the Dibranchiata belong the sin¬ 
gular fossil forms which are known to the geologist as Belem- 
nites. These singular forms are known almost solely by their 
complicated internal skeleton, and they appear to have abound¬ 
ed in the seas of the Secondary period. 

The second order of the Cephalopoda —that of the Tetra- 
branchiata —comprises forms characterized by being creeping 
animals, protected by an external , many-chambered shell , the 
partitions between the chambers being perforated for the pas¬ 
sage of a membranous or calcareous tube, termed the “ si¬ 
phuncle.” The arms are more than ten in number, and are 
devoid of suckers; the gills are four in number, two on each 
side of the body; the funnel does not form a complete tube; 
and there is no ink-bag. 

Though abundantly represented by many and varied fossil 
forms, the only living member of the Tetr abranchial a with 
which we are acquainted is the Pearly Nautilus, which has 
long been known by its beautiful chambered shell. The shell 
of the Pearly Nautilus (Fig. 91) is coiled into a spiral, and is 
many-chambered, the chambers being walled off from one an¬ 
other by curved shelly partitions or septa, perforated centrally 
by a foramen which transmits a membranous tube or siphuncle. 
The animal inhabits only the last and largest chamber of the 
shell, from which it can protrude its head at will. The func¬ 
tion of the chambers of the shell is not very clearly under¬ 
stood ; but it appears to be that of reducing the specific grav¬ 
ity of the shell to near that of the surrounding water; since 
they appear to be filled with some gas apparently secreted by 
the animal. The siphuncle does not communicate in any way 
with the chambers of the shell, and its functions are also un- 


CEPHALOPODA. 


193 


known, except that it must certainly serve to maintain the 
vitality of the shell. 


Fig. 91.—The Pearly Nautilus (Nautilus pompilius). a Mantle; b Its dorsal fold; c Hood; 
o Eye; t Tentacles; / Funnel. 

Of the fossil Tetrabrancliiata the most important are the 
Orthocerata and the Ammonites. The Orthocerata (Fig. 92) 
played a very important part in the seas of the Palaeozoic or 
Ancient-life period of the earth’s history, in which they ap¬ 
parently filled the place now taken by the predacious cuttle- 




Fig. 92 .—Orthoceras explorator. 1. Side view of a fragment showing the edges of the 
septa. 2. Transverse section of the same, showing the siphuncle («). (Billings.) 


fishes. They agreed with the Nautilus in having a many- 
- chambered shell, divided by curved partitions, perforated by a 
tube or siphuncle. The shell, however, differed from that of 
the Nautilus in not being curved or coiled up, but in being 






194 


INVERTEBRATE ANIMALS. 


straight. In other nearly-allied forms the shell was bent or 
even partially coiled up, but never so completely as in the 
true Nautilus . Many of the Orthocerata were of small size, 
but some of them were colossal, shells having been found of 
six or seven feet in length, and as thick as the body of a man. 

The Ammonites , with a number of allied forms of varied 
shapes and beautiful structure, appear to have taken the place 
of the Nautilidce , to a great extent, in the seas of the Second- 
arj' period; at which time, too, Dibranchiate Cephalopods first 
made their appearance. The true Ammonites resembled the 
Nautilus in having a many-chambered shell, which was coiled 
up into a spiral, but the position of the siphuncle was differ¬ 
ent, and the partitions or septa between the various chambers 
of the shell were wonderfully folded and lobed instead of 
being simply curved. The numerous beautiful shells allied to 
the Ammonites cannot be even mentioned here; but it is to 
be remembered that they are almost all characteristic of the 
Secondary period in geology, and that they are hardly known 
as occurring in the older period (Palaeozoic epoch). 


VERTEBRATE ANIMALS. 


CHAPTER XXIII. 


GENERAL CHARACTERS OF TIIE VERTEBRATA. 


The five sub-kingdoms which we have previously consid¬ 
ered, namely, the Protozoa , Ccelenterata , Annuloida , Annu- 
losa , and Mollusca , were grouped together by Lamarck into 
one great division, which he termed the Invertebrata . The 
remaining sub-kingdom, that of the Vertebrata , is so well 
marked and compact a division, and its distinctive characters 
are so numerous and so important, that this mode of viewing 
the animal kingdom is, at any rate, a very convenient one. 

The sub-kingdom Vertebrata includes the five great classes 
of the Fishes (Pisces), Amphibians, Reptiles, Birds (Aves), 
and Mammals; and the name of the'sub-kingdom is derived 
from the very general, though not universal, presence of the 
bony axis known as the “vertebral column” or backbone. 
One of the most fundamental of the distinctive characters of 
Vertebrate animals is to be found in the fact that the main 
masses of the nervous system (that is to say, the brain and 
spinal cord) are completely shut off from the general cavity 
of the body. In all Invertebrate animals (Fig. 93, A), the 
body may be regarded as a single tube, enclosing all the vis¬ 
cera ; and, consequently, when a distinct nervous system and 
alimentary canal are present, these are in no way shut off 
from one another. The transverse section, however, of any 
Vertebrate animal (Fig. 93, B) shows two tubes, one of which 
contains the great nervous axis (n!) or brain and spinal cord, 
while the other contains the alimentary canal, the chief circu¬ 
latory organs, and certain portions of the nervous system (: n ), 



196 


VERTEBRATE ANIMALS. 


which are known to anatomists as the “ sympathetic ” system. 
Leaving the brain and spinal cord out of sight for a mo¬ 
ment, we see that the lower or visceral tube of a Vertebrate 
animal contains the digestive canal (5), the blood-vascular sys¬ 
tem (c), and a system of nervous ganglia (n). Now, this is 



a 


A 


c 


Fig. 93. —Diagrams representing transverse sections of one of the higher Invertebrata, A, 
and one of the Vertebrata, B. a Wall of the body; & Alimentary canal; c Haemal or 
blood-vascular system; n Nervous system; n' Cerebro-spinal axis, or brain and spinal 
cord, enclosed in a separate tube; ch Notochord, or chorda dorsalis. 

exactly what is contained within the visceral cavity of any 
Invertebrate animal; and it follows from this that it is the 
“sympathetic” system of Vertebrate animals which is truly 
comparable with the nervous system of the Invertebrata. The 
brain and spinal cord, or “ cerebro-spinal axis,” are to be. looked 
upon as something not represented at all in the Invertebrata. 

Another peculiarity which is present in all the Vertebrata 
is, that at an early period of life there is developed, in the low¬ 
er wall of the tube which contains the cerebro-spinal axis, a 
singular structure known as the “ notochord ” (Gr. notos , back; 
chorde , string) (Fig. 93, B, ch). This is a semi-gelatinous rod, 
tapering at both ends, and extending along the floor of the 
cerebro-spinal tube. In some cases, the notochord remains 
permanently in this condition, but, in most cases, it is replaced 
at maturity by the bony column or backbone, from which the 
Vertebrata derive their name. The general structure of the 
vertebral column will be described shortly, and it is sufficient 
to state here that it consists of a series of more or less com¬ 
pletely bony segments or “ vertebrae,” arranged so as to form 
a longitudinal axis upon which the spinal cord is supported. 
It is to be remembered, however, that all Vertebrate animals 
do not possess a vertebral column. They all possess a noto¬ 
chord, but this may remain persistent throughout life, and, in 
many cases, the development of the spinal column is very im¬ 
perfect. 


GENERAL CHARACTERS OF THE VERTEBRATA. 197 

The skeleton of all Vertebrate animals is internal , and the 
muscles are attached to its several parts. The value of this 
character is in no way affected by the fact that many Verte¬ 
brates, such as the Tortoises, Crocodiles, and others, possess 
an external skeleton as well. The limbs of Vertebrate ani¬ 
mals are always articulated or jointed to the body, and they 
are always turned .away from that side of the body (the 44 neu¬ 
ral ” side) upon which the great masses of the nervous sj^stem 
are placed. The limbs may be altogether wanting, or partial-* 
ly undeveloped, but there are never more than two pairs , and 
they always have an internal skeleton for the attachment of 
the muscles of the limb. 

A distinct blood-vascular system is present in all Ver* 
tebrates, and in all except one—the Lancelet—there is a 
single contractile cavity or heart, furnished with valvular open¬ 
ings. 

Lastly, the masticatory organs of all Vertebrates are modi¬ 
fications of parts of the walls of the head, and are never 
modified limbs or hard structures developed in the mucous 
membrane of the digestive tube, as they are in the Inverte¬ 
brates. 

The above are the leading characters which distinguish the 
Vertebrata as a whole, and, before going on to consider the 
different classes, it may be as well to give a short and general 
sketch of the anatomy of the Vertebrates, commencing with 
their bony framework or skeleton. 

The skeleton of the Vertebrata may be regarded as con¬ 
sisting of the bones which go to form the trunk and head on 
the one hand, and of those which form the supports for the 
limbs on the other hand. The bones of the trunk and head 
may be regarded as essentially composed of a series of bony 
rings or segments, arranged longitudinally. Anteriorly, these 
segments are much expanded and also much modified to form 
the bony case which encloses the brain and which is termed 
the cranium or skull. Behind the head, the segments enclose 
a much smaller cavity in which is contained the spinal cord, 
and they are arranged one behind the other, forming the 44 ver¬ 
tebral column.” The segments which form the vertebral 
column are called 44 vertebras,” and they have the following 
general structure: Each vertebra (Fig. 94, A) consists of a 
central portion known as the 44 body,” or 44 centrum” (c), 
placed immediately below the spinal cord, and giving origin to 
certain 44 processes.” The ends of the bodies of the vertebrae 
are all united together in different ways, so as to give the col- 


198 


VERTEBRATE ANIMALS. 



Fig. 94.—A. Vertebra (lumbar) of the whale, c Centrum or body; n Neural arches; 
s Spinous process ; a Articular process ; d Transverse processes. ' B. Thoracic segment 
or vertebra, c Centrum of vertebra; n Neural arches, enclosing the canal for the spinal 
cord ; e Spinous process; r Bibs; p Costal cartilages; b Breastbone or sternum. (After 
Owen.) 

iimn great flexibility. From the back of the body of the ver¬ 
tebra proceed two bony arches which unite behind and thus 
form with the centrum a bony canal in which the spinal cord 
is contained. For this reason, these arches (n) are called the 
“ neural ” arches. From the point where the neural arches 
unite—that is to say, from the back of the neural canal—pro¬ 
ceeds a long process, sometimes cleft at its extremity, termed 
the “spinous process” (s). Springing also from each neural 
arch is a second shorter process (a) termed the “ articular pro¬ 
cess,” since by means of these, as well as by the bodies, the 
vertebrae are jointed or “ articulated ” together. Also arising 
from the neural arches at their junction with the body of the 
vertebra, there may be two lateral processes (d) which are 
called “ transverse processes.” This is the ordinary structure 
of the vertebra of a Mammal, and the names here used are 
those applied to the parts of the vertebra in human anatomy. 
In philosophical anatomy, however, these parts have proper 
technical names which can be employed for them in all animals 
alike. The nature of this work, however, will not allow of 
the introduction of these here. 

In the typical vertebra the segment is completed by a 
second arch, which is placed in front of or beneath the body 
of the vertebra, and which is known as the “ haemal ” arch, as 
it includes and protects the principal organs of the blood cir¬ 
culation (Fig. 94, B). This second arch is often only recog- 


GENERAL CHARACTERS OF THE VERTEBRATA. 199 


nizable with great difficulty, as its parts are generally much 
modified; but a good example may be obtained in the human 
chest. Here, attached to the front of the vertebra?, we find a 
series of bony arches, known as the ribs (r), followed by a 
series of cartilaginous pieces of a similar shape, termed the 
“ costal cartilages ” (/>), the whole united in front by a central 
bone, known as the breastbone or “ sternum ” ( b ). 


d 



Fig. 95. —Skeleton of the Beaver (Castor fiber), showing the regions of the vertebra 
column, c Cervical region, or region of the neck; d Dorsal region, or region of the 
back; b L umbar region , or region of the loins ; s Sacrum ; t Caudal region, or region 
of the tail. 


As a general rule, among the higher Vertebrates, the fol¬ 
lowing regions may be recognized in the vertebral column: 
Firstly, the cervical region (Fig. 95, c ), comprising a variable 
number of vertebrae, which constitute the neck, and immedi¬ 
ately follow the head. Secondly, the cervical region is suc¬ 
ceeded by a variable number of vertebrae which usually carry 
ribs, and are known as the dorsal vertebrae ( d ), or vertebrae 
of the back. Thirdly, come certain vertebrae which constitute 
the lumbar region (5), or the region of the loins. Fourthly, 
there usually follows a series of vertebrae which are immova¬ 
bly united together to form a single bone, which is termed the 
sacrum (s). Lastly, there comes a variable series of vertebrae 



200 


VERTEBRATE ANIMALS. 


which are usually free and movable upon one another, and 
which constitute the caudal region, or the region of the tail (£). 

The nature of the bones which enter into the composition 
of the limbs varies somewhat in different Vertebrates in ac¬ 
cordance with their mode of life; but in all the higher mem¬ 
bers of the sub-kingdom the limbs are built upon a general 


Fig. 96.—Fore-limb of the Chimpanzee, c Collar¬ 
bone, or clavicle; s Shoulder-blade, or scapu¬ 
la; I) Bone of the upper arm, or humerus; r 
Radius; u Ulna; d Bones of the wrist, or car¬ 
pus ; m Bones of the root of the hand, or me¬ 
tacarpus ; p Bones of the digits, or phalanges. 



Fig. 97.— Hind-limb of the Chimpan¬ 
zee. i Innominate bone; / Thigh¬ 
bone, or femur; t Tibia ; s Fibula; 
r Bones of the ankle, or tarsus; m 
Metatarsus; p Phalanges. 



and easily-recognizable type. The fore-limb consists generally 
of the folio wing parts: 1. A series of bones uniting the limb 
to the trunk, the two most important being the shoulder 
blade ( scapula ) and the collar-bone (clavicle) (Fig. 96, s and c) ; 
2. The bone which forms the upper portion of the limb proper, 
and which is known as the humerus ( b ). 3. Two bones which 
form the lower portion of the limb (e. g., the forearm in man), 









GENERAL CHARACTERS OF THE VERTEBRATA. 


201 


and which are known as the radius and ulna ( r and u ), of 
which the former is the bone mainly concerned in carrying the 
hand or fore-foot. 4. A number of small bones, which form 
the wrist, and are termed the carpus (d). 5. The cylindrical 

bones (usually fiye in number) which form the root of the 
hand, and are known as the metacarpus (m). 6. The bones 

which form the fingers proper, and which are known as the 
phalanges (p). 

Essentially the same parts can be traced in the hind-limb 
of a typical Vertebrate animal, but they are known by differ¬ 
ent names. The bones which unite the limb to the trunk are 
usually more or less completely united together, constituting 
a single mass, known as the innominate bone (Fig. 97, i). 
This is followed by a long, cylindrical bone, which forms the 
upper portion of the hind-limb, and is known as the “ thigh¬ 
bone,” or femur (f ). Following this are the two bones of 
the shank, corresponding to the radius and ulna of the fore¬ 
limb, and known as the tibia and fibula (t and s). Of these, 
the tibia (£) corresponds to the radius , and is mainly con¬ 
cerned in carrying the foot. Next comes a series of small 
bones, which form the ankle, and are known as the tarsus (r). 
This is succeeded by a series of cylindrical bones (usually five in 
number), which form the root of the foot, and which are termed 
the metatarsus (m). Finally, the metatarsus is succeeded 
by the bones of the toes, which in this case are again termed 
the phalanges ( p ). In both limbs the usual number of pha¬ 
langes to each toe or “ digit ” is three. 

The digestive system of the Vertebrata does not require a 
lengthened notice. The mouth is usually furnished with teeth , 
which have for their chief function the reduction of the food 
to a condition in which it can be digested. In some animals, 
however, such as the snakes, the teeth are only used to hold 
the prey, and not for mastication; and in others, such as the 
turtles and birds, the jaws are not furnished with any teeth 
at all. The food is also usually subjected in the mouth to the 
action of a special fluid—the saliva—which acts chemically as 
well as mechanically upon the food, and which is secreted by 
special glands, known as the “ salivary glands.” From the 
mouth the food passes through a muscular tube—the gullet, 
or oesophagus (Fig. 98, g) —to the proper digestive cavity, or 
stomach (i). Here it is subjected to the action of a special 
digestive fluid—the “ gastric juice ”—and is converted into a 
thick, pasty fluid, which is called chyme. From the stomach 
the chyme passes into a long, convoluted, muscular tube, which 


202 


VERTEBRATE ANIMALS. 


is called the “ small intestine ” (s?n). Here it is subjected to 
the action of two other digestive fluids, called the “ bile ” and 
“pancreatic juice,” as well as to the fluids secreted by the 
intestine itself. The bile is secreted by a large gland, which 
is known as the “ liver,” while the pancreatic juice is produced 
by another, termed the “ pancreas,” both pouring their secre¬ 
tion into the upper part of the small 
intestine. By the combined action 
of these digestive fluids the chyme 
is ultimately converted into a milky 
fluid, which is called chyle , when it 
is fit to be taken up into the blood¬ 
vessels. The small intestine finally 
opens into a tube of larger diameter, 
which is called the “ large intestine ” 
(Im), and this opens on the surface 
of the body by an anal aperture. In 
the large intestine the last remain¬ 
ing portions of the food which can 
be rendered useful are absorbed into 
the blood, the indigestible portions 
being ultimately got rid of as use¬ 
less. The fluid products of diges¬ 
tion (chyle) are chiefly absorbed 
from the intestinal canal by a set of 
special vessels, which are present in 
all Vertebrates, and which are called . 
the lacteals (Lat. lac , milk) from the 
milky fluid they contain. These 
lacteals combine to form a large 
trunk, by which their contents are 
ultimately added to the circulating 
blood. Part of the products of db 
gestion are absorbed by the veins 
which ramify on the intestinal canal, 
and which ultimately unite to form a great vessel, called the 
“ vena portae,” which goes to the liver. The materials, how¬ 
ever, which are taken up in this way also ultimately reach the 
(drculating blood. In this way, therefore, fresh matter is 
being constantly added to the blood to replace the waste 
caused by the performance of the vital functions. 

The blood is thus formed out of the materials which are 
taken into the alimentary canal as food; and in all the Yerte- 
brata (with one exception) it is of a red color, when viewed in 



Fig. 98. —Digestive system of a 
Mammal, g Gullet, or oesopha¬ 
gus; 8 Stomach; sm Small in¬ 
testine; Im Large intestine; r 
Large intestine terminating in its 
final portion, called the “rec¬ 
tum.” 






GENERAL CHARACTERS OF THE VERTEBRATA. 


mass. This is due to the presence in it of numerous micro¬ 
scopical particles, which are known as the “ blood-corpuscles,” 
the fluid itself being colorless. In Fig. 99 are represented 



Fig. 99— Blood-corpuscles, magnified, a Man; Z> Goose; c Crocodile; d Frog; e Skate. 


some of the forms of blood-corpuscles which are found in dif¬ 
ferent divisions of the Vertebrata. 

The blood is always distributed through the body by 
means of a system'of closed tubes, which constitute the “blood¬ 
vessels,” and, with the single exception of the Lancelet, it is 
always propelled by means of a contractile muscular cavity or 
“ heart.” The heart and other circulatory arrangements differ 
considerably in different classes of the Vertebrata , but these 
differences will be best considered at a later period. Respira¬ 
tion in all the Vertebrata is effected by means of distinct 
breathing-organs, assisted in many cases by the skin. In the 
water-breathing Vertebrates, such as fishes, the respiratory 
organs are in the form of gills or branchiae, which are richly 
supplied with blood, and are exposed to the influence of water 
holding oxygen in solution. In the air-breathing Vertebrates, 
the breathing organs are in the form of lungs. These essen¬ 
tially consist of cellular or spongy organs, placed in the cavity 
of the chest, richly furnished with blood-vessels, and receiving 
constant supplies of fresh air by means of a tube which opens 
in the throat and is known as the “ windpipe,” or trachea. In 
the higher Vertebrates the heart becomes a double organ, one 
side being concerned wholly with driving the impure ( venous ) 
blood to the lungs, while the other side propels the pure oxy¬ 
genated ( arterial ) blood to all parts of the body. 

The waste substances of the body—of which the most im¬ 
portant are water , carbonic acid , and the peculiar substance 
called urea —are got rid of by the skin and lungs, but prin¬ 
cipally by two glands which are called the kidneys. The ex¬ 
cretion of urea from the body, as a general rule, is wholly 
effected by means of the kidneys alone; and this is their most 
important function, as the retention of this substance within 
the body rapidly causes death. The secretion of the kidneys 
is sometimes got rid of by means of special canals appropriated 


204 


VERTEBRATE ANIMALS. 


to this alone; but in the lower Vertebrcita it is discharged in¬ 
to the hinder extremity of the alimentary canal, and is evacu¬ 
ated along with the undigested portions of the food. 

The nervous system varies greatly in its development in 
the Vertebrata. In the little fish called the Lancelet, the main 
mass of the nervous system consists of a cord of nervous mat¬ 
ter, representing the spinal marrow, but not having in front 
any enlargement which represents the brain. In all the other 
Vertebrata the central masses of the nervous system (termed 
the cerebro-spinal axis) consist of a nervous cord (the spinal 
cord) contained in the canal formed by the neural arches of 
the vertebrae, and of an anterior mass of nervous matter, which 
is protected by the skull, and is termed the encephalon or 
brain. The size and development, however, of the brain vary 
enormously in different Vertebrates; and in the lower forms 
the brain is little more than an aggregation or collection of 
nervous masses or “ ganglia,” which are connected with the 
special senses, sight, hearing, taste, and smell, special organs 
for which are present in almost all the Vertebrata. 

Reproduction in the Vertebrata is always truly sexual, the 
sexes are always in different individuals, and in no case are 
compound organisms produced by a process of budding or fis¬ 
sion. Most are oviparous , producing eggs from which the 
young are developed. Some retain the eggs within the bodj' 
till the young are ready to be hatched, and these are some¬ 
times said to be ovo-viviparous. The higher Vertebrates, 
however, bring forth their young alive, and are said to be 
viviparous (Latin, vivus , living; and pario , I bring forth). 

Primary Divisions or the Vertebrata. —The Verte¬ 
brata are variously divided into great primary sections by dif-' 
ferent writers, and all of these divisions have more or less 
merit. Here, however, the classification proposed by Prof. 
Huxley will be followed, and it is not necessary to enter into 
any consideration of the others. It has also been thought ad¬ 
visable to give in this place a brief account of the leading 
characters which separate these divisions from one another, 
though it is not to be expected that the learner will be able 
to appreciate the full value of these characters till he has com¬ 
pleted his study of the Vertebrata as a whole. 

The Vertebrata are divided by Prof. Huxley into the fol¬ 
lowing great divisions: 

I. Ichthyopsida (Gr. ichthus , a fish; and opsis , appear¬ 
ance).—In this section are included the fishes (Class Pisces ), 


GENERAL CHARACTERS OF THE YERTEBRATA. 205 


and the frogs, newts, and their allies (Class Amphibia). They 
are all characterized by the fact that they possess gills or 
branchiae, either throughout life or during the earlier stages 
of their existence; that they possess nucleated red blood' 
corpuscles (i. e., blood-corpuscles with a central particle or 
nucleus , Fig. 99, d, e), and by certain embryonic characters as 
well. From the temporary or permanent possession of gills, 
they are often spoken of as the Branchiate Vertebrates. 

II. Sauropsida (Gr. saura , a lizard; and ops is, appear¬ 
ance).—In this division are the birds (Class Aves), and the 
true reptiles (Class Beptilia). They are characterized by the 
fact that at no time of their life are they ever provided with 
gills; that the skull is jointed to the vertebral column by a 
single articulating surface (or condyle) ; that the lower jaw is 
composed of several pieces, and is united to the skull by 
means of a special bone (called the os quadratum) ; that they 
possess nucleated red blood-corpuscles (Fig. 99, b , c), and by 
certain embryonic characters as well.* 

III. Mammalia (Lat. mamma , the breast).—In this di¬ 
vision are all the ordinary quadrupeds; characterized by the 
constant absence of gills; by the skull being jointed to the 
vertebral column by two articulating surfaces (or condyles); 
by the fact that the lower jaw is composed of only two pieces, 
and is not united to the skull by means of a special bone (the 
quadrate bone); by having non-nucleated red blood-corpuscles 
(Fig. 99, a) ; and by having special glands — the mammary 
glands—which secrete a special fluid—the milk—by which 
the young are nourished for a longer or shorter period after 
birth. 

These three primary divisions comprise the five great 
classes into which the Vertebrata are divided: 

1. Fishes {Pisces). 

2. Amphibia (Frogs, Newts, etc.). 

3. Beptilia (True Reptiles). 

4. Aves (Birds). 

5. Mammalia. 

* Recent researches have led to the belief that the appearance of nuclei in the red blood- 
corpuscles of the Oviparous Vertebrates is due to changes taking place after death, and that 
these structures are not present during life. 

10 


ICHTHYOPSIDA. 


CHAPTER XXIV. 
CLASS I. PISCES. 


The fishes form the lowest class of the Vertebrata , and 
they may be broadly defined as being Vertebrate animals pro¬ 
vided with gills , whereby they are enabled to breathe air dis¬ 
solved in water; the heart , when present, consists of a single 
auricle and ventricle (with the exception of the mud-fishes) ; 
and the limbs , when present, are in the form of fins, or expan¬ 
sions of the integument. 

In their external form, fishes are in most cases adapted for 
rapid locomotion in water, the shape of the body being such 
as to cause the least possible friction in swimming. To this 
end, as well as for purposes of defence, the body is generally 
enveloped in a species of chain-mail formed by overlapping 
scales, to which bony plates, tubercles, and spines, are some¬ 
times added. Valuable characters can sometimes be drawn 
from the nature of the scales, and with a view to this the 
integumentary appendages of fishes have been divided by 
Agassiz as follows (Fig. 100): 

1. Cycloid scales («), consisting of thin, flexible, horny 
scales, which are circular or elliptical in shape, and have a 
smooth outline. These scales occur in most of our common 
fishes (e. g., the pike). 

2. Ctenoid scales (b). These resemble the cycloid scales 
in being thin, flexible, homy scales, but they are distinguished 
by having their hinder margins cut into comb-like projections, 
or fringed with spines. The common perch supplies a good 
example of these scales. 

3. Placoid scales (c). These are detached bony grains, 


PISCES. 


207 

tubercles, or plates, scattered through the skin, and sometimes 
armed with projecting spines. 

4. Ganoid scales (d~) composed of a layer of true bone 
covered by a layer of hard polished enamel. ‘ These scales are 
usually much thicker and larger than the ordinary scales; they 
are often oblong or rhomboidal in shape; they are often con¬ 
nected together by little processes; 
and they generally are in contact by 
their edges, but rarely overlap one 
another. In most fishes there is 
also to be observed a line of peculiar 
scales, forming what is called the 
u lateral line.” Each of the scales 
of this line is perforated by a minute 
tube, which leads into a longitudinal 
canal, believed to secrete the mucus 
with which the general surface is 
lubricated, or to have some sensory 
function. 

As regards the true internal 
skeleton, fishes differ very widely 
from one another, but the skeleton 
is so complicated that only a few of 
the most important points can be 
mentioned here. In one fish—the 
Lancelet—there can hardly be said 

to be any true skeleton, the vertebral column being repre¬ 
sented permanently by the semi-gelatinous notochord (Fig. 
105). In others, such as the Lampreys, Sturgeons, and Rays, 
the skeleton remains permanently in the condition of gristle 
(cartilage) ; in others it is partially cartilaginous and partially 
ossified; and, lastly, in most modern fishes it is completely 
converted into bone. The vertebral column in a bony fish 
consists of a number of vertebras which are hollow or cup¬ 
shaped at both ends (bi-concave or “ amphicoelous ”), the cup¬ 
like margins being united together by ligaments. The cavities 
formed by the apposition of the vertebras are filled with the 
gelatinous remains of the notochord. This gelatinous elastic 
substance acts as a ball-and-socket joint between the vertebras, 
thus giving the whole spine the extreme flexibility which is 
essential to animals living in a watery medium. * The entire 
spinal column is divisible into no more than two distinct 
regions, an abdominal and a caudal. The ribs are attached 
to the transverse processes or to the bodies of the abdominal 



Fig. 100.— Scales of different Fishes. 
a Cycloid scale (Pike); b Ctenoid 
scale (Perch); c Plaeoid scale 
(Thornback); d Ganoid scale (Pa- 
laoniscua). 





208 


VERTEBRATE ANIMALS. 


vertebrae (Fig. 101, r) ; and they do not enclose any thoracic 
cavity, or protect the organs which are usually contained in 
the chest — namely, the heart and breathing-organs. The 
anterior or lower ends of' the ribs of fishes are free, or are 
rarely united to hard productions of the integument; but there 
is never any breastbone or sternum properly so called. 



V 


Fig. 101.—Skeleton of the common Perch (Perea fluviatilis). p Pectoral fin; v One of the 
ventral fins; a Anal fin, supported upon interspinous bones (i); cCaudal fin; d First 
dorsal fin; d' Second dorsal fin, both supported upon interspinous bones; i i Interspinous 
bones; r Ribs; s Spinous processes of vertebrae; h Haemal processes of vertebrae. 

The only remaining bones of the trunk proper are the so- 
called “ interspinous bones ” (Fig. 101, i i). These are a series 
of pointed, dagger-like bones, imbedded in the middle line of 
the body, between the great lateral muscles which form the 
greater part of the body of a fish. The inner ends or points 
of the interspinous bones are attached by ligament to the 
spinous processes of the vertebras, and at their outer ends they 
support the framework (rays) of the so-called “ median ” fins. 
As a rule there is only one interspinous bone to each vertebra, 
but in the flat-fishes (Sole, Turbot, etc.) there are two. The 
limbs of fishes may be wholly wanting, or one pair may be ab¬ 
sent, but in no case is the number greater than the regular 
vertebrate type—namely, two pairs. When developed, how¬ 
ever, the limbs of fishes are very different from those of other 
Vertebrates, consisting of expansions of the integument, 
furnished with bony or gristly supports or rays, and thus con¬ 
stituting what are called “fins” (Fig. 102). The pair of limbs 
which correspond to the arms of man and to the fore-limbs of 
other Vertebrates are termed the pectoral fins, and they are 



riscES. 


209 


attached to a bony arch which is attached either to the back 
of the skull or to the spinal column (Fig. 101, y>, and 102, p). 
The hind-limbs in fishes are known as the ventral fins (Figs. 
101, 102, u), and are not only often wanting altogether, but 
when present are less developed than the pectorals and less 
fixed in their position. They are united to an imperfect bony 


Fig. 102.—Outline of a Fish (Perea granulata ), showing the “paired” and “median” tins. 
p Pectoral fin; v Ventral fin; d First dorsal fin; d' Second dorsal fin; c Caudal fin; 
a Anal fin. 



arch, which represents the innominate bones, or pelvic arch, 
of the higher Vertebrates, but which is never joined to the 
spinal column. In some fishes the ventral fins are placed far 
back, and in these the bony arch which supports them is freely 
suspended in the muscles. In others the ventral fins are alto¬ 
gether out of position, and are placed beneath, or even in 
front of the pectoral fins; and in these cases the pelvic arch is 
attached to part of the pectoral arch. The pectoral and ven¬ 
tral fins represent, as just said, the fore and hind limbs, and 
consequently there are always two of each, when they are 
present at all. They are, therefore, spoken of as the “ paired ” 
fins. Besides these, however, or in the absence of one or 
other of these, there is also a series of what are called “ me¬ 
dian ” fins; that is to say, fins which are placed in the middle 
line of the body, and which are unpaired , having no fellows. 
These median fins agree with the paired fins in being expan¬ 
sions of the integument, supported by bony or gristly supports 
or “ rays,” and they are carried by the heads of the “ inter- 
spinous” bones, already described (Fig. 101, it), They are 



210 


VERTEBRATE ANIMALS. 




Fig. 108. — Tails of different Fishes. 
a Homoccrcal tail (Sword-fish); b 
Heterocercal tail (Sturgeon). 


variable in number, and in some cases there is only a single 

fringe running round the hinder 
extremity of the body. Common¬ 
ly, however, the median fins con¬ 
sist of one or two expansions of 
the dorsal integument, called the 
“dorsal” fins (Fig. 101, d d') ; one 
or two on the ventral or lower 
surface near the vent, called the 
“ anal ” fins (a) ; and a broad fin 
at the extremity of the vertebral 
column, constituting the “ caudal ” 
fin or tail (c). 

The tail in all fishes is placed 
vertically—that is to say, it strikes 
the water laterally, or from side to 
side, and it is the chief organ of 
progression in the fish. Two very 
distinct types of tail are found 
among the fishes. In one of these, 
found in most living forms, the tail is composed of two nearly 
equal lobes which spring from the end of the spine (Fig. 103, 
a). This form of tail is said to be “ homocercal.” In the 
other type of tail, found in the dog-fishes, sharks, and other 
living fishes, as well as in many extinct forms, the tail is un¬ 
equally lobed, and is said to be “heterocercal” (Fig. 103, b). 
In these forms the vertebral column is prolonged into the 
upper lobe of the tail, and the greater portion of the tail is 
found below the spine. 

In both the paired and the median fins the integument is 
supported by a series of spine-like bones, which are called 
“ rays.” These rays are sometimes simple undivided rays or 
spines, when the}^ are called “ spinous rays” (Fig. 101, d ); but 
in other cases they are both divided by transverse joints, and 
split up into numerous longitudinal branches toward their ex¬ 
tremities, when they are spoken of as “ soft rays ” (Fig. 101, 
d'). The soft rays occur in many fishes in different fins, but 
they are invariably present in the caudal fin or tail. 

As regards the digestive system in fishes, the mouth is 
usually furnished with a complicated system of teeth, de¬ 
veloped not only upon the jaws, but upon any or every bone 
which enters into the composition of the oral cavity. The 
gullet opens into a stomach, usually of large size, and its hin¬ 
der aperture (the pylorus ) is usually furnished with a valve> 




riscES. 


211 


Immediately behind the pyloric opening of the stomach there 
is usually a variable number of blind tubes (called the “ py¬ 
loric caeca ”) which open into the intestine, and which are be¬ 
lieved to represent the pancreas. In some fishes, however, 
there is a well-developed pancreas, and in others even these 
tubes are wanting. The intestinal canal is a longer or shorter, 
more or less convoluted tube, and its absorbing surface is 
sometimes largely increased by a spiral folding of the mucous 
membrane, which winds like a screw in close turns from the 
pylorus to the anus. The liver is usually of large size, and 
saturated with oil, but in the Lancelet it is doubtfully rep¬ 
resented by a hollow, sac-like organ. The kidneys in fishes 
are of great comparative size, forming two elongated organs, 
situated beneath the spine, and extending along the whole 
length of the abdomen. 

Respiration in all fishes is aquatic, and is effected by means 
of gills or branchiae , in all except the Lancelet, in which res¬ 
piration is effected by branchial filaments placed round the 
pharynx, and also by a greatly-developed pharynx perforated 
by ciliated apertures (Fig. 105). The arrangement and struct¬ 
ure of the gills in fishes vary a good deal in different orders, 
and the leading modifications will be noticed hereafter. In 
the mean while it will be sufficient to give a short description 
of the branchial apparatus in one of the bony fishes. In such 
a fish the gills consist of a single or double series of flat carti¬ 
laginous leaflets, covered by mucous membrane, richly supplied 
with blood, and arranged on bony or cartilaginous arches 
which are connected with the tongue-bone (hyoid bone) below 
and with the under surface of the head above. The branchial 
arches and branchiae are suspended in cavities placed on the 
side of the neck, and in the ordinary bony fishes there is only 
one such cavity on each side. The water is taken in at the 
mouth by a process analogous to swallowing, and it gains ad¬ 
mission to the branchial chamber by means of a series of clefts 
or slits which perforate the sides of the pharynx. Having 
passed over the gills and lost its oxygen, the effete water 
makes its escape behind by an aperture called the “gill-slit,” 
which is placed on the side of the neck. The opening of the 
gill-slit is closed in front by a chain of flat bones which con¬ 
stitute the “ gill-cover,” and by a membrane which is sup¬ 
ported upon a variable number of slender bony spines. This 
is the general mechanism of respiration in one of the bony 
fishes, but different arrangements are found in other cases, 
which will be subsequently noticed. 


212 


VERTEBRATE ANIMALS. 


The heart in fishes may be regarded as essentially a 
branchial or respiratory heart, being concerned chiefly with 
driving the venous and impure blood to the gills. It con¬ 
sists in almost all cases of two 
cavities, an auricle and a ventricle 
(Fig. 104). The auricle (a) receives 
the venous blood which has passed 
through all the various parts of the 
body, and propels it into the ven¬ 
tricle (v). From the ventricle pro¬ 
ceeds a single great vessel (the 
“branchial artery”), the base of 
which is usually developed into a 
muscular cavity, the “ bulbus arte¬ 
riosus” (m), which acts as a kind of 
additional ventricle. By the ventri¬ 
cle and bulbus arteriosus the venous 
blood is driven to the gills, where it 
is subjected to the action of the wa¬ 
ter. The aerated blood is not re¬ 
turned to the heart, but is driven 
from the gills through all parts of 
the body, the propulsive force neces¬ 
sary for this being derived partly 
from the heart, and partly from the 
contractions of the muscles between 
which the blood-vessels pass. The 
Fig. 104.—Diagram of the Circuia- essential peculiarity of the circulation 

tion in a Fish. The arterial sys- r n i , • ± i ii 

tern is represented, black 5 the Oi tlSilGS COIlSIStS in tlllS^ tllcit tllG ctr- 

venous system isleft light. oAu- terialized blood returned from the 

ride, receiving the venous blood t , •, 

from the body; v Ventricle; m gills IS propelled through the gen- 

.Tr“ ra “hivl“d eral vessels of the body (systemic 
to the gills (&); c Great systemic vessels) without being sent back to 
to the tissues. the heart. In the Bancelet, alone 

of all fishes, there is no single heart, 
and the circulation is effected by means of contractile dila¬ 
tations situated upon several of the vessels. In the Mud¬ 
fish (Lepidosiren) the heart consists of two auricles and a 
ventricle. In all cases the blood is cold, or, in other words, 
has a temperature very little, or not at all, higher than that 
of the surrounding medium. The blood-corpuscles (Fig. 99, 
e) are always nucleated, and, except in the Lancelet, are 
most of them red. 

While the respiration of all fishes is truly aquatic, most 








PISCES. 


213 


are, nevertheless, furnished with an organ which doubtless 
corresponds to (or is homologous with) the lungs of the higher 
Vertebrata. This is known as the “ air ” or “ swim bladder,” 
and is a sac filled with gas and situated between the alimen¬ 
tary canal and the kidneys. In most cases, the sac contains 
only a single cavity, but, in many instances, it is variously 
divided by partitions. In most fresh-water fishes, the gases in 
the swim-bladder are mainly composed of nitrogen, but, in the 
sea fishes, it is chiefly filled with oxygen. The sac of the 
swim-bladder is often closed, but, in other cases, it opens into 
the gullet by means of a duct which corresponds to the wind¬ 
pipe. In the great majority of fishes, the functions of the 
air-bladder are mainly hydrostatic, that is to say, it serves to 
maintain the necessary agreement between the specific gravity 
of the fish and that of the surrounding water. In the singu¬ 
lar Mud-fish (. Lepidosiren ), the air-bladder is composed of two 
distinct sacs, divided into a number of cellular compartments, 
and opening into the gullet by a tube. In this fish it acts as 
a respiratory organ, and is, therefore, not only in structure, but 
also in function, the representative of the lungs of the other 
Vertebrates. 

The nervous system of fishes is of an inferior type of or¬ 
ganization, the brain being of comparatively small size, and 
consisting mainly of a collection of ganglia. As regards the or¬ 
gans of the senses, two peculiarities deserve notice. In the first 
place, though fishes possess the essential parts of the organ 
of hearing, they possess no external ears, and in no case is 
there any direct communication between the ear and the outer 
world. In the second place, the organs of smell consist of a 
double cavity lined by a mucous membrane folded into numer¬ 
ous plaits, into which water is admitted, usually by two dis¬ 
tinct apertures or nostrils. Behind, however, the nasal sacs 
are closed, and they do not communicate by any aperture with 
the throat, as they do in all the higher Vertebrates. The only 
exceptions to this rule are the Hag-fishes and their allies 
( Myxinoids ) and the Mud-fish ( Lepidosiren ). 

As regards their reproductive system, most fishes are truly 
oviparous , and the ovaries are familiarly known as the “ roe.” 
Some fishes are ovo-viviparous, retaining their eggs within the 
body till the young are hatched. The male organs of repro¬ 
duction are commonly spoken of as the “ milt ” or “ soft roe.” 


CHAPTER XXV. 


ORDERS OF FISHES. 

The number of different kinds of fisbes is so enormous that 
nothing further will be attempted than merely to give an out¬ 
line of the leading peculiarities which distinguish the different 
orders. The classification here adopted is the one proposed 
by Prof. Huxley, who divides the class Pisces into the follow¬ 
ing six orders: 

1. Pharyngobranchii. 

2. Marsipobranchii . 

3. Teleostei. 

4. Ganoidei. 

5. Elasmobranchii. 

6. Dipnoi. 

Order I. Pharyngobranchii (Gr. pharugx , the upper part 
of the gullet, and bragchia , gills).—This order of fishes in¬ 
cludes only a single animal, the anomalous Amphioxus , or 
Lancelet, the organization of which differs in almost all its 
important points from that of all the other members of the 
class. In fact, the Lancelet presents us with the lowest type 
of organization as yet known in the I T ertebrata. The Lance¬ 
let is an extraordinary little fish, from one and a half to two 
inches long, which burrows in sand-banks in various seas, but 
is especially abundant in the Mediterranean. The body is 
lanceolate in shape, and is provided with a narrow membra¬ 
nous border, of the nature of a median fin, which runs along 
the whole of the dorsal and a portion of the ventral surface, 
and expands at the tail to form a lancet-shaped caudal fin. 
There are no true “ paired ” fins, representing the fore and 
hind limbs. The mouth is a longitudinal fissure, placed at the 
front of the head, and completely destitute of jaws, but sur- 


ORDERS OF FISHES. 


215 


rounded by a number of cartilaginous filaments. The throat 
is provided with several leaf-like filaments, which are richly 
supplied with blood, and are believed to discharge in part the 
function of gills. The mouth (Fig. 105, m) opens into a 
dilated chamber, which is believed to represent the pharynx, 
and is termed the pharyngeal or “branchial” sac. The walls 
of this chamber (p) are strengthened by numerous cartilagi- 



Fig. 105.—Diagram of the Lancelot (Amphioxus lanceolatus). m Mouth with cartilagi¬ 
nous filaments ; p Greatly-developed pharynx, or branchial sac, perforated by ciliated 
apertures; i Intestine; a Anus; h Blood-vessels, with pulsating dilatations in place 
of a heart; ch Notochord; n Spinal cord. 

nous filaments, between which are a series of transverse slits 
or clefts, and the whole is covered with a richly-ciliated mu¬ 
cous membrane. The function of this sac is clearly respiratory, 
the w^ater from without being admitted through the mouth, 
passing through the branchial clefts into the abdominal cavity, 
and finally escaping by means of an aperture placed on the 
ventral surface a little in front of the anus. From the hinder 
end of the branchial sac proceeds the alimentary canal, which 
has appended to it a sac-like organ, believed to represent the 
liver, and which terminates behind in a distinct anal aperture. 
There is no heart, and the circulation is entirely effected by 
means of several contractile dilatations, developed upon the 
great blood-vessels (h). The blood itself is colorless. No 
kidneys have hitherto been discovered, and the reproductive 
elements are emitted into the abdominal cavity, from which 
they escape by the pore placed upon the low^er surface. 

There is no skeleton properly so called. The notochord 
(ch) remains throughout life as a semi-gelatinous rod, enclosed 
in a membranous sheath, and supporting the spinal cord. 
There is no skull, and the spinal cord ( n) does not expand in 
front to form a distinct brain. The brain, however, may be 
said to be represented, as the front portion of the nervous 
axis gives off nerves to a pair of eyes, and another branch to 





216 


VERTEBRATE ANIMALS. 


a ciliated pit, which is believed to be a rudimentary organ of 
smell. 

Order II. Marsipobranchii (Gr. marsipos , a pouch; brag- 
chia , gills).—This order includes the Hag-fishes ( Myxinidce ) 
and the Lampreys (. Petromyzonidve ), and it is defined by the 
following characters: The body is cylindrical and worm-like, 
and is destitute of limbs. The skull is cartilaginous, there is 
no lower jaw, and the notochord remains through life, so that 
there is no vertebral column. The heart is composed of an 
auricle and a ventricle, but there is no bulbus arteriosus. The 
gills are pouch-like, communicating w 7 ith the throat on the 
one hand, and opening externally on the other by means of 
apertures placed on the sides of the neck. 

The Hag-fish ( Myxine ) is an eel-like fish, which agrees 
with the Lampreys in having neither pectoral nor ventral fins, 
the representatives of the fore and hind limbs. The mouth is 
of a very.remarkable character, and enables the Hag-fish to 
lead a very peculiar existence. It is generally found imbedded 
in the interior of some large fish, into which it has penetrated 
by means of a single serrated and recurved fang attached to 
the centre of the palate. The mouth itself is destitute of 
jaws, and forms a sucking disk or cup. Another remarkable 
peculiarity of the Hag-fishes is found in the structure of the 
nose. In all fishes, namely, except these and the Mud-fish 
(Lepidosiren ), the nasal chambers are closed behind, and do 
not communicate with the cavity of the mouth, as they do in 
the higher Vertebrates. In the Myxinoids, however, such a 
communication does exist. The nasal sacs are placed in com¬ 
munication with the throat (pharynx) by means of a canal 
which perforates the palate. A second canal leads from the 
nasal cavities in front to open by an external aperture (the 
nostril or “ spiracle ”) on the top of the head behind the 
mouth. 

Another peculiarity, which is best considered in the Lam¬ 
preys, is to be found in the structure of the respiratory or¬ 
gans, from which the name of the order is derived. When 
viewed externally, instead of the single great “ gill-slit,” cov¬ 
ered by a “ gill-cover,” as seen in the ordinary bony-fislies, the 
side of the neck presents seven round holes placed far back 
in a line on each side. These holes are the external apertures 
of the gills (Fig. 106, A), which in these fishes are in the 
form of sacs or pouches, the lining membrane of which is 
thrown into numerous folds or plaits, over which the branchial 


ORDERS OF FISHES. 


217 


vessels ramify (Fig. 106, B). Internally the sacs communi¬ 
cate with the cavity of the pharynx, by means of a common 
respiratory tube into which they all open. It follows from 
this arrangement that the gill-pouches on the two sides of the 
neck communicate freely with one another through the phar¬ 
ynx. The object of this arrangement is to obviate the ne¬ 
cessity for admitting the water to the gills through the mouth. 



Fig. 106.—A, Lamprey ( Petromyzon ), showing the sucking-mouth and the apertures of 
the gill-sacs. B, Diagram to illustrate the structure of the gills in the Lampreys, a 
Pharynx; b Tube leading from the pharynx into one of the gill-sacs; c One of the gill- 
sacs, showing the lining membrane thrown into folds; d External opening of the gill- 
sac. (In reality the gill-sacs do not open directly into the pharynx, but into a common 
respiratory tube which communicates with the pharynx; but this is omitted for the 
sake of clearness.) 


as ordinary fishes do. These fishes are in the habit of fixing 
themselves to foreign objects by means of the suctorial mouth ; 
and, when in this position, it is, of course, impossible that 
they can obtain the necessary water of respiration through the 
mouth. As the gill-sacs, however, on the two sides of the 
neck communicate freely with one another through the phar¬ 
ynx, water can readily pass in and out. The gills are not 
provided with cilia, but the circulation of water is assisted by 
a kind of elastic cartilaginous framework upon which the 
whole respiratory apparatus is supported, and which acts some¬ 
what like the ribs of the higher Vertebrates. 

The nasal cavities of the Lampreys, unlike those of the 
Myxinoids, are closed behind, and do not communicate with 
the throat. Some of the Lampreys are permanently inhabit¬ 
ants of rivers, but the great sea-lamprey (.Petromyzon mari- 
nus ) only quits the salt water and betakes itself to fresh in 
order to deposit its eggs. 

Order III. Teleostei (Gr. teleios , perfect; and osteon , 
bone).—The fishes comprised in this order, as implied in their 
name, have a well-ossified or bony skeleton, and they are com- 




218 


VERTEBRATE ANIMALS. 


monly known as the <£ bony ” fishes. In all the Teleostei , the 
skeleton is bony, the skull is composed of distinct bones, and 
there is a lower jaw. The vertebral column always consists 
of more or less completely ossified vertebrae; and the two 
pairs of limbs, when present, are in the form of fins, supported 
by rays. The gills are free, comb-like or tufted in shape, and 
always protected by a bony gill-cover. The bulbus arteriosus 
is not capable of regular contractions, and is separated from 
the ventricle by only a single valve. 

The order Teleostei comprises almost all the most familiar 
fishes, and it will be unnecessary to dilate here upon their 
structure, as they were taken as the type of the class in de¬ 
scribing the fishes generally. It may be as well, however, to 
recapitulate some of the leading points in the anatomy of the 
bony fishes. 1. The skeleton is always more or less complete¬ 
ly ossified, and does not remain cartilaginous throughout life. 
The notochord is not permanent, and the vertebral column 
consists of a number of distinct vertebrae. The vertebrae, 
however, are “ amphicoelous,” or hollow at both ends, so that 
there is left between each pair a doubly-conical cavity, which 
is filled with the cartilaginous or semi-gelatinous remains of 
the notochord. In this way an extraordinary amount of flexi¬ 
bility is given to the entire vertebral column. In no fish (ex¬ 
cept the Bony Pike, which belongs to another order) is the 
conversion of the bodies of the vertebrae into bone carried 
further than this. 

2. The integument usually develops scales, and these in 
the great majority of cases are of the forms known as “ cy¬ 
cloid” and “ctenoid,” the former being circular or elliptical 
horny plates, with plain margins ; while the latter have their 
hinder margins cut into comb-like projections, or fringed with 
spines (Fig. 100, a , b). 

3. The anterior and posterior limbs are usually, but not 
always, present, and when developed they are always in the 
form of fins. These fins may be supported by “ spinous rays ” 
or “ soft rays,” or by both. The spinous rays are simple un¬ 
divided bony spines which taper to a point. The soft rays 
are doubly divided, splitting up toward their extremities into 
a number of secondary rays, and being also divided by trans¬ 
verse joints into numerous short pieces. 

4. Besides the “ paired ” fins which represent the limbs, 
there is also a series of unpaired or “ median ” fins, the rays 
of which are supported upon a series of dagger-shaped bones, 
deeply plunged in the flesh in the middle line of the body, 


ORDERS OF FISIIES. 


219 


and known as the “ interspinous ” bones (Fig. 101). The me¬ 
dian fins are variable in number, but when fully developed 
they consist of one or two fins on the back (the dorsal fins), 
one or two on the ventral surface (the anal fins), and one 
clothing the posterior extremity of the body (the caudal fin, 
or tail, Fig. 102). In all the Teleostei , the caudal fin has the 
shape called “ homocercal ” —that is to say, it consists of two 
equal lobes—and the vertebral column is not prolonged into 
the upper lobe (Fig. 103, a). 

5. The heart consists of two cavities, an auricle and a ven¬ 
tricle, but the bulbus arteriosus is not rhythmically contractile, 
and is separated from the ventricle by only a single pair of 
valves. 

6. The respiratory organs are in the form of free, comb¬ 
like, or tufted gills, enclosed in two cavities placed on the 
sides of the neck. Each of these branchial chambers opens 
externally by a single aperture, the “ gill-slit,” which is pro¬ 
tected by a chain of bones, forming the “ gill-cover,” and by 
a membrane supported by bony rays. Internally the branchial 
chambers communicate with the throat by a series of clefts or 
fissures, and the water required in respiration is taken in at 
the mouth by a process analogous to swallowing. 

7. The nasal sacs never communicate behind with the 
throat (pharynx). 


Tabular View of the Main Divisions of the Teleostei. 

Sub-order I. Malacopteri. —Usually a complete series of fins, supported 
by rays, all of which are soft , or many-jointed (with the occasional exception 
of the first rays in the dorsal and pectoral fins). A swim-bladder is always 
present, and is always connected with the gullet by a duct. The skin is rarely 
naked, and is mostly furnished with cycloid scales, but sometimes ganoid 
scales are present. 

Among the more important families in this sub-order are the Eels (Mn- 
rcenidce), Herrings ( Clupeidce ), Pikes ( Esocidce ), Carps ( Cyprinidce ), Salmon 
and Trout ( Salmonidce ), and Sheat-fishes ( Stturidce ). 

Sub-order II. Anacanthini. —Fins entirely supported by soft rays, and 
never by spinous rays. Ventral fins either wanting, or placed under the 
throat, beneath or in advance of the pectorals. 

The two leading families in this sub-order are the Cod, Ling, and Haddock 
family ( Gadidce ), and the Flat-fishes (Pleuronectidce), comprising the Sole, 
Turbot, Flounder, and others. 

Sub-order III. Acanthopteri. —Fins with one or more of the first rays in 
the form of undivided, inflexible, spinous rays. Scales mostly ctenoid. Swim- 
bladder without a duct. 

The leading families in this order are the Wrasses ( Cyclo-labridce ), the 
Perches ( Percidce ), the Mackerels ( Scomberidce ), the Mullets ( Mugilidce ), and 
the Gobies ( Gobiidce). 


220 


VERTEBRATE ANIMALS. 


Sub-order IV. Plectognathi.— Certain of the bones of the mouth (the 
maxillary and prse-maxillary bones) immovably connected on each side of 
the jaw. Integumentary skeleton in the form of ganoid plates, scales, or 
spines. 

The chief families in this sub-order are the File-fishes ( Balistidce ), and the 
Trunk-fishes ( Ostraciontidce). . _ 

Sub order V. Lophobranchii. —Gills arranged in little tufts on the 
branchial arches. Integumentary skeleton in the form of ganoid scales. 

The two families contained in this division are the Sea-horses ( Hippocam- 
pidce ), and the Pipe-fishes ( Syngnathidce ). 

Order IV. Ganoidei (Gr. ganos , splendor, or brightness). 
—The fourth order of fishes is that of the Ganoidei , including 
few living forms, but having a great and varied development 
in past geological epochs. The Ganoid fishes are dis¬ 
tinguished by the imperfect development of the skeleton, 
which is mostly cartilaginous throughout life, and by having 
an integumentary skeleton composed of ganoid scales, plates, 
or spines (Fig. 100, d). The skull is composed of distinct 
bones, and there is always a lower jaw. There are usually 
two pairs of fins' (pectoral and ventral), supported by many 
series of cartilages, and the ventral fins are placed very far 
back. The first rays in the fins are usually in the form of 
strong spines. The caudal fin or tail is mostly heterocercal 
or unsymmetrical (Fig. 103, b). The swim-bladder is always 
present, is often cellular, and is provided with an air-duct. 
The gills and gill-covers are essentially the same as in the 
bony fishes. The heart has one auricle and a ventricle ; and 
the bulbus arteriosus is rhythmically contractile, is furnished 
with a distinct coat of muscular fibres, and is furnished with 
several transverse rows of valves. 

The best known of the living Ganoids are the Bony Pike 
( ~Lepido$teus\ the Sturgeon ( Sturio ), and the JPolypterus. Of 
these, the Bony Pike is found in the rivers and lakes of North 
America. It is a large fish, attaining a length of several feet, 
and it has the body entirely covered with an armor of ganoid 
scales arranged in obliquely transverse rows. The jaws form 
a long, narrow snout, armed with a double series of teeth, and 
the tail is heterocercal. The vertebral column is more perfect¬ 
ly ossified than in any other fish, the bodies of the vertebrae 
being convex in front and concave behind ( “ opisthocoelous ”). 
The Polypterus (Fig. 107, A) inhabits the rivers Nile and 
Senegal, and is remarkable for the peculiar structure of the 
dorsal fin, which is broken up into a series of small, detached 
portions, each composed of a single spine in front, with a soft 
fin attached to it behind. Some of the species of Polypterus 


ORDERS OF FISHES. 


221 


d 



Fig. 107.—Ganoid Fi?hes. A. Polypterus , a living Ganoid. B, Oeteolepis , a fossil Ganoid 
(restored): a Pectoral fin; b Ventral fin; c Anal fin; d d' Dorsal fins. 


are stated to possess external gills when young, which they 
lose w-hen grown up, thus making an approach to the Am¬ 
phibia. Many of the fossil Ganoids are more or less closely 
allied to the living Lepidosteus and Polypterus. 

Another great group of the Ganoid fishes is represented by 
the Sturgeons (SturionicCee), in which the skeleton is always 
very imperfectly ossified, and the head, with more or less of 
the body, is protected by large ganoid plates, which are often 
united together at their edges by sutures. The true Sturgeons 
are chiefly found in the North Sea, the Caspian, and the Black 
Sea, and 'they are captured when ascending the great rivers 
for the purpose of spawning. The swim-bladder of the Stur¬ 
geons is one of the chief sources from w T hich isinglass is pre¬ 
pared, and the roe is sold as a delicacy under the name of 
caviare. The place of the Sturgeons in North America is 
taken by the Paddle-fishes ( Spatularia ). 

The group of Ganoids represented at the present day by 
the Sturgeons and Paddle-fishes w T as formerly represented by 
numerous remarkable fishes, which are most abundant in the 
system of rocks known to geologists as the “ Old Red Sand¬ 
stone.” The graphic descriptions of Hugh Miller have placed 
many of these fishes before us as living pictures, but space 
will not allow of any further notice of them here. One, how¬ 
ever, of the more striking forms is figured hereafter (Fig. 108). 

Order V. Elasmobranchii (Gr. elasma , a thin plate; and 
bragchia , gills).—This order includes the Sharks and Rays, 







222 


VERTEBRATE ANIMALS. 


and is distinguished by the following characters : The skull 
and lower jaw are well developed, but the skull is not com- 



Fig. 108 .—Cephalaspis Lyeilii , from the Old Red Sandstone of Scotland. 

7 

posed of distinct bones, and simply forms a kind of cartila¬ 
ginous box. The vertebral column is sometimes cartilaginous, 
sometimes composed of distinct vertebrce. The integument¬ 
ary skeleton is in the form of placoid scales (Fig. 100, c )— 



Fig. 109.—Elasmobranchii. A. White Shark {Carcharias). B. King of the Herrings 

(Chimcera). 











ORDERS OF FISHES. 


223 


tliat is to say, of detached grains, tubercles, or plates. There 
are two pairs of fins, corresponding to the fore and hind limbs, 
and the ventral fins are placed far back, close to the anus. 
The heart consists of an auricle and ventricle; and the bulbus 
arteriosus is rhythmically contractile, is provided with a dis¬ 
tinct coat of muscular fibres, and is furnished with several 
transverse rows of valves.. The gills are fixed, and form a 
number of pouches, which open internally into the pharynx, 
and communicate with the outer world by a series of aper¬ 
tures placed on the side of the neck (Fig. 109). The intestine 
is very short, but, to compensate for this, the mucous mem¬ 
brane is thrown into a fold, which winds round the intestine 
in close turns from the pyloric orifice of the stomach to the 
anus, and which thus greatly increases its absorbing surface. 

The best-known members of this order are the Sharks and 
Rays, but numerous extinct forms testify to its great abun¬ 
dance in past geological epochs. 


Tabular View of the Divisions of the Elasmobranchii. 

Sub-order I. Holocephali. —The mouth placed at the end of the head, 
and the external opening of the gills in the form of a single gill-slit. 

The best-known member of this sub-order is the Cliimcera monstrosa , 
sometimes called the “ King of the Herrings.” 

Sub-order II. Plagiostomi. —Mouth transverse, placed on the under sur¬ 
face of the head ; external opening of the gills in the form of several slits on 
each side of the neck, not protected by a gill-cover. 

Fam. a. Cestraphori. — Ex. Port-Jackson Shark. 

Fam. b. Selachii. — Ex. Sharks and Dog-fishes. 

Fam. c. Batides. — Ex. Rays. 


Order YI. Dipnoi (Gr. di, double; pnoe, breath).—This 
order is a very small one, and includes only the very singular 
Mud-fishes ( Lepidosiren ),* which are of great interest from 
the many points of affinity which they exhibit to the Am¬ 
phibia. The body of the Mud-fish (Fig. 110) is completely 
fish-like, and is protected by a covering of small, horny, over¬ 
lapping scales, which have the cycloid characters. There are 
two pairs of limbs, but these are in the form of awl-shaped 
organs, each supported by a single jointed cartilaginous rod. 
The pectoral limbs have a membranous fringe inferiorly, and 
the ventrals are placed very far back. There is also a median 

* Recently a singular fish has been discovered in the rivers of Queensland (Australia), 
which will probably have to be referred to the order Dipnoi; but our knowledge about it is 
still imperfect. 


224 


VERTEBRATE ANIMALS. 


fin behind, forming a continuous fringe round the compressed 
tail, and supported by cartilaginous rays. 



P 


Fig. 110 .—Lepidosiren annectens, the Mud-fish, p Pectoral limbs; v Ventral limbs. 

The skull is composed of distinct bones, and there is a 
lower jaw, but the notochord is persistent, and there are no 
bodies of vertebrae developed. The respiratory organs are 
twofold , consisting, firstly , of free filamentous branchiae or 
gills, contained in a branchial chamber, which opens externally 
by a single vertical gill-slit; and, secondly , of true lungs, in 
the form of a double cellular air-bladder communicating with 
the gullet by means of an air-duct or windpipe. Sometimes, 
if not always, there are rudimentary external gills as well, 
placed on the side of the neck. The heart consists of a ven¬ 
tricle, and of two auricles, divided from one another by an 
incomplete partition. Lastly, the nasal sacs open behind into 
the throat, and do not form closed chambers opening only by 
the nostrils, as they do in all other fishes, except the Myxi- 
noids. The two best-known species are the Lepidosiren 
paradoxa from the Amazons, and the L. annectens from the 
Gambia. They both inhabit marshy tracts, and both appear 
to be able in the dry season to bury themselves in the mud, 
and to form a kind of chamber, in which they remain dormant 
till the rains of the wet season set them free- 


ICHTHYOPSIDA. 

CHAPTER XXVI. 

CLASS II. AMPHIBIA. 

This class of Vertebrata comprises the Frogs and Toads, 
the Newts and Land-salamanders, the Ccecilice, and some ex¬ 
tinct forms, and it may be briefly defined as follows: In all 
cases gills or branchiae adapted for aquatic respiration are pres¬ 
ent during a part or the whole of life; but, in all cases, true 
lungs adapted for breathing air are ultimately developed, even 
when the gills are retained through life. All pass through 
some sort of a metamorphosis after being set free from the 
egg. The limbs may be absent or there may be only one 
pair, but in no case are they ever converted into fins. When 
median fins are present, as is sometimes the case, these are 
never furnished with fin-rays or interspinous bones, as in the 
fishes. The skull always articulates with, or is jointed to, the 
spinal column by two articular surfaces or condyles. The 
heart consists of two auricles and a single ventricle. The na¬ 
sal sacs always open behind into the mouth; and there is a 
common cavity or “ cloaca ” which receives not only the ter¬ 
mination of the intestine (rectum), but also the ducts of the 
kidneys and of the reproductive organs. 

The great and distinguishing character of the Amphibia 
(Gr. amphi , both ; bios, life) is, that they invariably undergo 
some kind of metamorphosis after birth, though, in some rare 
cases, the eggs are retained so long within the body of the 
parent that there is little or no obvious change. In the great 
majority of cases, however, the Amphibians commence life as 
water-breathing larva?, provided with gills ; but, in their adult 
state, they possess true air-breathing lungs, the gills sometimes 
disappearing when the lungs are developed, but being some- 


226 


VERTEBRATE ANIMALS. 


times retained throughout life. Most Amphibians, therefore, 
are to a greater or less extent amphibious , that is to say, 
more or less capable of living indifferently either on land or 
in the water. In the majority of cases, the gills are external , 
placed on the sides of the neck, and not contained in a special 
cavity, thus differing altogether from the gills of fishes. In 
the Frogs and Toads, and in some others, there are two sets 
of gills, one external and the other internal, of which the for¬ 
mer is soonest lost. The lungs of the Amphibians never attain 
a very high state of development, and, in those forms in which 
the gills are retained throughout life, the chief business of 
respiration appears to be carried on by the gills. In accord¬ 
ance with the changes in the respiratory process, correspond¬ 
ing alterations take place in the blood-vessels. With the 
development of the lungs, the vessels which carry blood to 
them (the pulmonary arteries) increase in size, while the 
branchial vessels which carry the blood to the gills undergo a 
proportionate diminution. At first, the condition of the circu¬ 
lation is very much the same as it is in fishes, but ultimately 
it becomes nearly the same as in the true reptiles. 

The Amphibia are divided into three living and one ex¬ 
tinct order, as follow: 

1. Ophiomorpha . 

2. Urodela. 

3. Anoura. 

4. Labyrinthodontia . 

Order I. Ophiomorpha (Gr. ophis , a serpent; and morphe , 
form).—This order is an extremely small one, and, as its name 
implies, it comprises certain snake-like Amphibians. The order 
includes only the curious animals known as Coecilice , which are 
found in Java, Ceylon, South America, and Guinea. The body is 
entirely destitute of limbs, and is enclosed in an integument 
which is thrown into numerous transverse wrinkles, and some¬ 
times has numerous horny scales imbedded in it. The eyes are 
concealed by the skin, and are rudimentary. There is no tail, 
and the anal aperture is placed almost at the extreme end of 
the body. When adult, respiration is carried on by means of 
lungs, but gills are present in the young, and there can, there¬ 
fore, be no doubt as to their being genuine Amphibians. 

The CcBciliae are found burrowing in marshy ground, and 
they are not unlike large earth-worms in appearance, but they 
sometimes attain a length of several feet. 


AMPHIBIA. 


227 



Fig. 111 .—a Siphonops annulatus , one of tho Caecilians, much reduced ; b Head of the 
same; c Mouth, showing the tongue, teeth, and internal openings of the nostrils; d 
Tail of the same. (After Dumeril and Bibron.) 


Order II. Urodela or Iciitiiyomorpha (Gr. ichthus , a 
fish, and morphe , shape).—In this order are a number of fish¬ 
like Amphibians, of which the Neivts and Land-salamanders 
are the most familiar examples. In all the members of this 
section, the skin is naked, and never develops any hard struct¬ 
ures, and in all there is a well-developed, fish-like tail, which 
is retained throughout life. The vertebrae are sometimes hol¬ 
low at both ends ( amphicoelous ), sometimes hollow behind 
and convex or rounded in front ( opisthocoelous ). The ribs are 
rudimentary and the bones of the forearm ( radius and ulna ), 
and of the shank ( tibia suidfibula), are separate, and are not 
combined so as to form single bones. 

The Iciitiiyomorpha are not unfrequently spoken of as the 
“ Tailed ” Amphibians ( Urodela ), and they fall into two natu¬ 
ral sections, according as the gills are permanently retained 
throughout life, or are cast off before maturity is attained. 
The animals belonging to the first section are often called 
“ perennibranchiate,” while those belonging to the second are 
said to be “ caducibranchiate.” 

Among the Perennibranchiate forms, in which the gills are 
permanently retained after the lungs make their appearance, 
the best-know T n examples are Axolotl (Fig. 112), the curious 
Proteus anyuinus , and the Mud-eel {Siren). The Axolotls 











228 


VERTEBRATE ANIMALS. 


inhabit various of the lakes of the American Continent, the best- 
known species being the Siredon pisciforme of the Mexican 
lakes (Fig. 112). It attains a length of a foot or more, and 



Fig. 112.— The Axolotl (Siredon pisciforme). (After Tegetmeier.) 


possesses both pairs of limbs, the fore-feet having four toes, 
the hind-feet five toes. The branchiae are in the form of three 
long ramified processes on each side of the head; and the tail 
is compressed, and fringed by a fin which is prolonged on the 
back between the shoulders. In a state of nature, the Axolotl 
is certainly perennibranchiate, and it breeds freely in this 
condition. It has been shown, however, by Prof. Marsh, of 
New Haven, that some species, when kept in confinement, lose 
their gills, and undergo certain other changes, becoming ul¬ 
timately converted into a Salamandrcid, apparently belonging 
to the genus Amblystoma . The Proteus is an extraordinary 
Amphibian which is found inhabiting the waters of caves in 
Illyria and Dalmatia. It attains a length of about a foot, and 
is of a pale flesh-color or nearly white. The gills, which are 
retained throughout life, are of a bright scarlet. Both pairs 
of limbs are developed, but they are only short and weak, the 
fore-limbs having three toes each, and the hind-limbs only 
two. The eyes are extremely small, the animal spending its 
^ existence in darkness; and swimming is effected mainly by 
means of the tail. The Siren , or Mud-eel, is a large lizard-like 
Amphibian, which is found abundantly in the swamps of South 
Carolina, and attains the great length of three feet. The ex¬ 
ternal branchiae are retained throughout life, and they are the 
main organs of respiration. The fore-limbs are present, but 
the hinder pair of limbs is never developed. 




AMPHIBIA. 


229 


The “caducibranchiate” section of this order is charac¬ 
terized by the fact that both pairs of limbs are always de¬ 
veloped, and the branchiae are never retained throughout life. 
The most familiar examples are the Water-salamanders or 
Newts (Triton), and the Land-salamanders. The Newts (Fig. 
113) are well known as inhabiting pools in many countries, 



Fig. 113.—The great Water-Newt (Triton cristatus), male. (After Bell.) 


and the young lead a strictly aquatic life. When the lungs 
are developed the external gills wholly disappear, and the 
respiration becomes strictly aerial, though the animals still 
spend a great part of their time in the water. The larva or 
young form is at first destitute of limbs, and the fore-limbs are 
the first to be developed, the reverse of this taking place in 
the Frogs. In accordance with their mode of life, the tail is 
compressed and flattened, so as to form an efficient swimming 
apparatus. The Water-salamanders are all oviparous, and the 
young are like the tadpoles of the common frog. 

The Land-salamanders, in both their adult and young 
state, live upon land, and the tail is rounded and cylindrical. 
The young are not developed in water, but are retained with¬ 
in the body of the parent for a longer or shorter period, so 
that the reproduction becomes ovo-viviparous, or even vivip¬ 
arous. The best-known Salamanders occur upon the Con¬ 
tinent of Europe, and one species is singular in the fact that 
it inhabits high mountains. 

It is important to remember in connection with all these 
“ tailed ” Amphibians, that they are wholly distinct from the 
true Lizards, with which they are often confounded. Many 
of them are completely lizard-like in form, having a long tail 
and two pairs of legs; all, however, at some time or other in 
their life, respire by means of gills, and this is never the case 
with any true Lizard. It must be confessed, however, that a 



230 


VERTEBRATE ANIMALS. 


near approach to the Lizards is made by the Land-salamanders, 
the young of which have sometimes lost their gills before 
birth. 

f 

Order III. Anoura or Theriomorpha (Gr. ther, a beast; 
and morphe , shape).—This order is the highest of the Am- 
phibia , and comprises the Frogs and Toads. It is sometimes 
known by the name of Batrachia (Gr. batrachos , a frog), or 
Anoura (Gr. a , without; owra, a tail), the latter name being 
derived from the fact that the adults are “ tailless.” 

The tailless Amphibia or Theriomorpha are characterized 
by the fact that while the larva possesses a tail, and is fur¬ 
nished with gills, the adult has no tail, and breathes wholly 
by lungs. Both pairs of limbs are always developed in the 
full-grown animal, and the hind-limbs are usually considerably 
longer than the fore-limbs, and generally have the toes 
webbed, while those of the fore-limbs are free. The skin is 



Fig. 114.—Anoura. Tree-frog (IJyla leucotcenia). (After Gunther.) 


soft, and there are rarely any traces of any integumentary 
skeleton. The spinal column “(Fig. 114) is short; the dorsal 
vertebrae are very long; and the ribs are quite rudimentary, 
their place being taken by greatly-developed transverse pro¬ 
cesses. The bodies of the vertebrae are hollow in front and 
convex behind ( procoelous ). The bones of the forearm ( radius 
and ulna), and those of the shank (tibia and fibula ), are united 
together to form single bones. The upper jaw is usually fur- 


AMPHIBIA. 


231 


nished with teeth, and the lower jaw sometimes, but there 
are no teeth in the Toads. The lungs are well developed, 
comparatively speaking; and, as there are no ribs by which 
the cavity of the chest can be expanded, the air is taken into 
the lungs by a process nearly akin to that of swallowing. 
There can be no doubt, also, that the skin plays a very im¬ 
portant part in the aeration of the blood, and that the frogs, 
especially, can carry on their respiration by means of the skin 
without the assistance of the lungs for a very lengthened 
period. This, however, should not lead to any credence being 
given to the often-repeated stories of frogs and toads being 
found in closed cavities in solid rock, no authenticated instance 
of such an occurrence being known to science. The ova of 
the frogs and toads are deposited, in masses or strings, in 
water, and the young or larvrn are familiar to every one as 
tadpoles. Upon its escape from the egg, the young frog (Fig. 



Fig. 115.—Development of the common Frog, a Tadpole, viewed from above, showing the 
external branchiae (g ); b Side view of a somewhat older specimen, showing the fish-like 
tail; c Older specimen, in which the hind-legs have made their appearance; d Specimen 
in which all the limbs are present, but the tail has not been wholly absorbed. (After 
Beii.) 


115) presents itself as a little fish-like creature with a broad 
head, a sac-like belly, and a long, compressed tail with which 
it swims actively. It breathes by means of gills or branchiae, 
of which there are two sets, one external, and the other in¬ 
ternal ; at first there are no limbs; but, as development pro¬ 
ceeds, the limbs make their appearance—the hind-legs first, 
and then the fore-legs. The tail, however (Fig. 115), is still 
retained as an instrument of progression. Ultimately, when 







232 


VERTEBRATE ANIMALS. 


the limbs are fully developed, and the gills have given place 
to lungs, the tail disappears, and the animal now takes to the 
land as a perfect frog. 

The development of the Frog is a good illustration of the 
general zoological law, that the transitory embryonic stages 
of the higher members of any division of the animal kingdom 
are often represented by the permanent condition of the lower 
members of the same division. Thus the transitory condition 
of the young Frog, in which it breathes by external branchiae, 
is to a certain extent permanently represented by the perma¬ 
nent condition of a perennibranchiate Amphibian, such as the 
Proteus. The stage at which the external branchiae have dis¬ 
appeared, but the tail is still present, and the limbs are de¬ 
veloped, is permanently represented in the common tailed 
Amphibians, such as the Newts. 

The order Anoura comprises the three families of the 
Frogs, Toads, and Surinam Toads. The Frogs {Ranidce) are 
distinguished by having a tongue which is fixed to the front 
of the mouth, and can be protruded at will, while the upper 
jaw is always armed with teeth. The typical Frogs have 
enormously-developed hind legs, the toes of which are united 
by membrane, or are “ webbed.” They swim very power¬ 
fully, and can take extensive leaps. The Tree-frogs (Fig. 
114), on the other hand, are adapted for a wholly different 
life, inhabiting trees, among which they climb with great ease 
by the help of suckers developed upon the ends of the toes. 
They are mostly found in warm countries, especially in Amer¬ 
ica, but one species is European. 

In the equally familiar Toads (Bufonidoe) the structure of 
the tongue is the same as in the Frogs, but the jaws are not 
furnished with teeth. In the Surinam Toads ( Pipidce ) there 
is no tongue at all, and usually no teeth. 

Order IV. Labyri:nthodontta. —This, the last order of 
the Amphibia , is not represented by any living forms, and re¬ 
quires to be little more than mentioned. The Lab}^rinthodonts 
were Amphibia which were mostly of large size, and of which 
some must have obtained absolutely gigantic dimensions, the 
skull of one species being three feet in length and two in 
breadth. They were first known to science simply by their 
footprints, which were found in certain Secondary sandstones 
{Trias). These footprints consisted of a series of alternately 
placed pairs of hand-shaped impressions, the hinder print of 
each pair being much larger than the fore one. So like were 


AMPHIBIA. 


233 


these prints to the shape of the human hand that the unknown 
animal which had produced them was christened the “ Gheiro - 
therium ” (Gr. cheir, hand; ther, beast). Further researches, 
however, showed that these footprints were produced by 
various species of large Amphibians, to which the name of 
JLabyrinthodontia was applied, in consequence of the compli¬ 
cated microscopic structure of the teeth. These extinct Am¬ 
phibians are known to have existed at the time of the Coal, 
but they are most characteristic of the period known to geolo¬ 
gists as the Trias. 


SAUROPSIDA. 


CHAPTER XXVII. 

CLASS m. REPTILIA. 

We commence now the second great primary division of 
the Vertebrata , namely, that of the Sauropsida , comprising 
the Reptiles and the Birds. These two classes, though very 
unlike in external appearance, are united by the following 
characters: There are never .at any period of life gills or bran¬ 
chiae adapted for aquatic respiration ; the red corpuscles of 
the blood are nucleated (Fig. 99, 5, c ); the skull articulates 
with the vertebral column by means of a single articulating 
surface or condyle; each half of the lower jaw is composed 
of several pieces, and is jointed to the skull, not directly, but 
by the intervention of a special bone (the so-called “ quadrate 
bone ”). 

These being the characters by which, among others, Rep¬ 
tiles and Birds are collectively distinguished from other Ver¬ 
tebrates, it remains to see what are the characters by which 
the Reptiles are distinguished, as a class, from Birds. In all 
Reptiles the blood is cold—that is to say, very slightly warm¬ 
er than the temperature of the external medium in which they 
live. The integument secretes scales, with or without bony 
plates, but in no case do the integumentary appendages take 
the form of feathers. The heart consists of two auricles, and 
a ventricle, which in most is partially divided into two cham¬ 
bers by an incomplete partition, and in a few is completely 
divided. In any case, however, more or less of the impure 
venous blood is mixed with the pure arterial blood which cir¬ 
culates over the body. There is no division between the cavi¬ 
ties of the thorax and abdomen, and the lungs are not con¬ 
nected with air-sacs placed in various parts of the body. The 
limbs may be wanting, or rudimentary, but in no case are the 


REPTILIA. 


235 


fore-limbs constructed upon the type of the “ wing ” of birds, 
and in no living Reptile is there the bone which is known in 
Birds as the “ tarso-metatarsus.” 

The class Reptilia includes the Tortoises and Turtles ( Ghe- 
lonia ), the Snakes ( Ophidia ), the Lizards (Lacertilia), and the 
Crocodiles ( Crocodilia ). With the exception of the Tortoises 
and Turtles, they are mostly of an elongated cylindrical form, 
furnished behind with a long tail. The limbs may be alto¬ 
gether absent or quite rudimentary, as in the Snakes, but in 
almost all the higher members of the class there are two pairs 
of limbs, which may be either adapted for walking or swim¬ 
ming, and which in some extinct forms support a flying mem¬ 
brane. The internal skeleton is always bony, never cartila¬ 
ginous or semi-cartilaginous as in many of the fishes. The 
skull is joined to the spine by a single articulating surface (or 
condyle). The lower jaw is complex, each half being com¬ 
posed of several pieces united by sutures. In Tortoises and 
Turtles, however, these separate pieces are amalgamated to¬ 
gether, and the two halves are also united, so that the whole 
lower jaw appears to form a single piece. In most Reptiles, 
on the other hand, the two halves of the lower jaw (Fig. 116) 
are only loosely united; in the Snakes by ligaments and mus¬ 
cles, in the Lizards by gristle, and in the Crocodiles by suture. 



Fig. 116.—Skull of a Serpent (Python), a Quadrate bone; b Lower jaw, articulating with 
the movable quadrate bone. 


In all, the lower jaw is jointed to the skull by means of a 
special bone, called the “ quadrate bone; ” and as this often 
projects backward, the opening of the mouth is often very 
extensive, and may even extend backward beyond the base of 
the skull (Fig. 116, a). Teeth are generally present, but these 
are used chiefly to hold the prey, and notin biting or chewing 




236 


VERTEBRATE ANIMALS. 


the food. Except in the Crocodiles, the teeth are not sunk 
into distinct sockets, and they are usually replaced as fast as 
shed. They likewise do not differ from one another sufficient¬ 
ly in form or function as to allow of their being divided into 
different sets, as they can be in the Mammals. Usually the 
teeth are confined to the jaws proper, but in some cases they 
are carried by other bones of the mouth. In the Tortoises 
and Turtles there are no teeth, and the jaws are simply 
sheathed in horn, so as to constitute a kind of beak, like that 
of a bird. The integumentary skeleton is in the form of 
scales, sometimes combined with bony plates. In the Tor¬ 
toises and Turtles the integumentary skeleton is so united 
with the true skeleton as to form a kind of bony case or box, 
in which the body is enclosed. 

The digestive system presents little worthy of special no¬ 
tice, except that the termination of the intestine ( rectum ) opens 
into a cavity called the “ cloaca,” which receives also the ducts 
of the urinary and generative organs. 

It is, however, in the structure of the circulatory and respir¬ 
atory organs that the most important characters of the Reptiles 
are to be looked for. The heart in all Reptiles may be regarded 
as being, in function^ three-chambered, being composed of two 
auricles and a single ventricle, imperfectly divided by an in¬ 
complete partition. In the Crocodiles alone the heart is, struct¬ 
urally , four-chambered, the ventricle being divided into two 
by a complete partition. Here, however, the same results are 
brought about as in the other Reptiles, by means of a commu¬ 
nication which subsists between the great vessels which spring 
from the ventricles thus formed. In the ordinary Reptiles the 
course of the circulation is as follows (Fig. 117): The impure 
or venous blood that has circulated through the body is poured 
by the great veins into the right auricle (a). The pure or 
arterial blood that has been submitted to the action of the 
lungs is poured by the pulmonary veins into the left auricle 
(a!). Both auricles empty their contents into the ventricle, 
and, as the partition which divides the ventricle is an incom¬ 
plete one, it follows that the venous and arterial streams must 
mix to a greater or less extent in the ventricle. From the 
ventricle arise the great vessels which carry the blood to the 
lungs and to all parts of the body, and it follows, as a matter 
of necessity, that all these parts are supplied with a mixed 
fluid, consisting partly of impure or venous blood, and partly 
of pure or arterial blood. In the Crocodiles, in which there 
are two ventricles completely separated from each other, the 


REPTILIA. 


237 


same result is brought about by means of a communication 


great vessels which spring 


P *** 


which takes place between the 
from the ventricles, in the imme¬ 
diate neighborhood of the heart. 

From this brief description it 
will be seen that the peculiarity 
of the circulation in Reptiles con¬ 
sists in the fact, that the lungs 
and all parts of the body are sup¬ 
plied with mixed blood; whereas 
in the higher Vertebrates the 
lungs are supplied with pure 
venous blood, and the various tis¬ 
sues of the body with pure arte¬ 
rial blood. 

As regards the structure of 
the lungs, it is merely to be noted 
that there is no partition ( dia¬ 
phragm or midriff) separating 
the two cavities of the thorax and 
abdomen, and that the lungs, 
therefore, often attain a great pro¬ 
portionate size, sometimes ex¬ 
tending through almost the whole 
length of the cavity of the trunk. 

There are also no air-sacs commu¬ 
nicating with the lungs, as in the 
Birds. 

Lastly, all Reptiles are essen¬ 
tially oviparous, some being ovo- 
viviparous. The egg-shell is usu¬ 
ally parchment-like, but in other 
cases contains more or less cal¬ 
careous matter. 

The class Peptilia is divided into four living and five ex¬ 
tinct orders, as follows, but the latter require but brief notice: 

1 . Chelonia (Tortoises and Turtles). 

2. Ophidia (Snakes). 

Lacertilia (Lizards). 

Crocodilia (Crocodiles). 

Ichthyopterygia ' 

Sauropterygia 
Pterosauria 
Anomodontia 
Deinosauria 



Fig. 117.—Diagram of the circulation of 
a Eeptile. a Eight auricle, receiving 
venous blood from the body; a' Left 
auricle, receiving arterial blood from 
the lungs; v Arterio-venous ventri¬ 
cle, containing mixed blood, which is 
driven by (p) the pulmonary artery to 
the lungs, and by ( o ) the aorta to the 
body. (The venous system is left light, 
the arterial system is black, and the 
vessels containing mixed blood are 
cross-shaded.) 


Extinct. 





CHAPTER XXVIII. 


DIVISIONS OF REPTILIA, 

Order I. Chelonia (Gr. chelone , a tortoise).—In this 
order are included the various Tortoises and Turtles, charac¬ 
terized by having the body enclosed in a bony case or box, 
and by the fact that the jaws are not provided with teeth, but 
are encased in horn, so as to form a kind of beak. The case 
in which the body of a Chelonian is protected is composed 
partly of integumentary plates, and partly of flattened bones 
belonging to the true skeleton, and it is composed essentially 
of two pieces, one placed on the back and the other on the 
lower surface of the body, firmly united together at their edges. 
The dorsal shield is more or less convex and rounded, and is 
called the carapace (Fig. 118, ca ); while the ventral shield is 
more or less completely flat or concave, and is called the plas¬ 
tron. The carapace and plastron, as just said, are united by 
their edges, but they leave two openings, one in front for the 
head, and one behind for the tail. The carapace is essentially 
composed of the flattened and expanded spinous processes of 
the vertebras and the greatly-developed ribs, covered by a 
series of horny plates. These are growths of the integument, 
and in some cases they constitute the “ tortoise-shell ” of com¬ 
merce. The plastron is also composed partly of bony and 
partly of horny plates, but opinions differ as to whether the 
bony plates are to be looked upon as formed by an expanded 
breastbone, or whether they are merely integumentary, the 
probabilities being in favor of the latter view. 

The remaining peculiarities with regard to the skeleton 
which deserve special mention are: Firstly, that the dorsal 
vertebras are immovably connected together,’so that this region 
of the spine is quite inflexible; secondly, that the heads of the 
ribs are articulated directly to the bodies of the vertebras; and, 


DIVISIONS OF REPTILIA. 


239 


thirdly, that the scapular and pelvic arches, supporting respec¬ 
tively the fore and hind limbs, are situated within the carapace 
(Fig. 118, s and jp), so that the shoulder-blade is placed inside 
the ribs instead of outside, as is usually the case. 



Fig. 118. —Skeleton of a Tortoise ( Emys EuropcecC ), seen from below, the plastron haying 1 
been removed, ca Carapace, showing the flattened and expanded ribs; « Scapular 
arch, carrying the fore-limbs, and placed in the interior of the carapace; p Pelvic arch, 
carrying the hind-limbs; r Bibs. 

The Chelonia are conveniently divided into groups, accord¬ 
ing as the limbs are adapted for swimming (natatory), or for 
progression on land (terrestrial); or, again, enable the animal 
to lead an amphibious life, sometimes on land and sometimes 
in the water. Of the strictly aquatic forms the best known 
are the edible Green Turtle ( Chelonia mklas ) and the Hawk’s- 
bill Turtle ( Chelonia imbricata). The former is found abun¬ 
dantly in many of the seas of warm climates, and is largely 
imported into Europe as a delicacy. The latter (Fig. 119) is 
truly a native of warm seas, though an occasional straggler 
has reached the shores of Britain. It is of comparatively 
small size—not more than about three feet in length—but is 




240 


VERTEBRATE ANIMALS. 



of considerable commercial importance, as it furnishes the 
“ tortoise-shell ” of trade, so largely used in various kinds of 
ornamental work. 


Fig. 119.- -The Hawk-billed Turtle (Chelonia imbrieata). (After Bell.) 

The Sea-tortoises or Turtles have the carapace much flat¬ 
tened, the legs of unequal length, in the form of solid fins or 
oars, the toes being conjoined, and hardly distinct from one 
another. 

The Marsh, Pond, and River Tortoises are generally fur¬ 
nished with webbed feet, and lead an amphibious, semi-aquatic 
existence. The so-called “ Soft Tortoises ” ( Trionycidce) be¬ 
long here, and are distinguished by the imperfect condition 
of the carapace, which is simply covered with a leathery skin. 
A good example is the Soft-shelled Turtle (T. ferox) of the 
Southern States. Here also belong the Snapping-turtles, so 
well known in the person of the common American species 
(Chelydra serpentina ), and the Terrapins (. Emydidoe ), of 
which many forms are found in all parts of the United States. 
In the curious little Box-tortoise (Cistudo Virginea ) the plas¬ 
tron is composed of two movable portions which can be 
brought into accurate apposition with the carapace, thus com¬ 
pletely protecting the animal within. 

The Land Tortoises have short legs of nearly equal length, 
the toes little distinct, and united into a sort of stump, with 
indistinct, horny claws. Good examples of this group are the 


DIVISIONS OF IiEPTILIA. 


241 


common European Tortoise (Testudo Grceca) and the Indian 
Tortoise ( T\ Indica ), the last attaining a length of over three 
feet. 

Order II. Ophidia (Gr. ophis, a serpent).—This order in¬ 
cludes most of the animals which would commonly be called 
snakes or serpents, and is characterized by the following pecu¬ 
liarities : The body is always more or less elongated, worm¬ 
like or cylindrical, and the skin develops horny scales, but 
never bony plates. There is never any breastbone (sternum), 
nor pectoral arch, nor fore-limbs; nor, as a rule, are there any 
traces of hind-limbs. In a few cases, however, rudimentary 
hind-limbs can be detected. The ribs are always very numer¬ 
ous. The two halves of the lower jaw are composed of several 
pieces each, and they are united to one another in front only 
by ligaments and muscles (Fig. 120). Hooked, conical teeth 



Fig. 120.—The Naja Haje, a poisonous Snake of Egypt. 


are always present, but they are never lodged in distinct 
sockets, and are only used to "hold the prey, and not in masti¬ 
cation. The lungs and other paired organs are often not sym¬ 
metrical, one of each pair being usually smaller than the other, 
or altogether absent. 


242 


VERTEBRATE ANIMALS. 


The most striking of these characters of the snakes is to 
be found in the nature of the organs of locomotion. The 
fore-limbs are invariably altogether wanting, and there is no 
pectoral arch nor breastbone; and the hind-limbs are either 
totally absent or are at best rudimentary and never exhibit 
any outward evidence of their existence, beyond the occasion¬ 
al presence of short, horny claws or spurs. In the entire ab¬ 
sence, then, or rudimentary condition of the limbs, the snakes 
progress by means of the ribs, which are always excessively 
numerous, and, in the absence of a breastbone, are also ex¬ 
tremely movable. Their free ends, in fact, are simply attached 
by muscular fibres to the scales or “ scutes,” which cover the 
lower or abdominal surface of the animal. The number of 
ribs varies from 50 up to 320 pairs, and, by means of this 
arrangement, the snakes are able to progress rapidly, walking, 
as it were, upon the ends of the ribs. Their movements are 
also much assisted by the extreme flexibility of the whole 
spine, caused by the cup-and-ball articulation of the bodies of 
the vertebras, each of which is concave in front and convex 
behind (procoelous). 

Of the other characters of the snakes, a few words may be 
said as to the tongue, the eye, and the teeth—all important 
structures in this order. The tongue , in serpents, is probably 
more an organ of touch than of taste, and consists of two 
muscular cylinders, which are united toward their bases. The 
forked organ thus formed can be protruded and retracted at 
w T ill, being in constant vibration when protruded, and being 
in great part concealed by a sheath when retracted. The eye 
of serpents (Fig. 121, A) is not protected by any eyelids, and 
hence the peculiar stony and unwinking stare for which these 
reptiles are celebrated. In place of eyelids, the outer layer 
of the skin is prolonged over the eye as a continuous and 
transparent film, behind which is a chamber formed by the 
mucous covering of the eye, into which the tears are dis¬ 
charged. The outer membrane is periodically shed along with 
the rest of the external or epidermic layer of the integument, 
and is again renewed. The pupil is round in most serpents, 
but it forms a vertical slit or fissure in the venomous snakes 
and in the Boas. 

As regarcls the teeth, it is to be noticed that the snakes 
are not in thbbabit of chewing their prey, but of swallowing 
it whole, and the construction of their dental apparatus is in 
accordance with this peculiarity. The lower jaw, as before 
said, articulated with the skull by means of a quadrate bone 


DIVISIONS OF REPTILIA. 


243 


(Fig. 117), and this in turn is movably jointed to the cranium. 
The two halves of the lower jaw are also merely united 
loosely in front by ligaments and muscles. In consequence 
of this peculiar arrangement of parts, the serpents have the 
power of opening the mouth to an extraordinary width, and 
they can perform the most astonishing feats in the w T ay of 
swallowing. The teeth are simply fitted for seizing and hold¬ 
ing the prey, but not in any way for chewing or dividing it. 
In the harmless snakes, the teeth are in the form of solid 
cones, which are arranged in rows round the whole of the 
upper and lower jaws, a double row existing on the palate 
as well. In the venomous snakes, on the other hand, the 
ordinary teeth are usually wanting upon the upper jaws, and 
these bones are themselves much reduced in size. In place 
of the ordinary teeth, however, the upper jaws carry the so- 
called “ poison-fangs ” (Fig 121, B). These are a pair of long, 



Fig. 121.—A, Diagrammatic Section of the Eye of a Viper (after Cloquet), a Eyeball; & 
Optic nerve; c Chamber into which the tears are poured ; d Epidermic layer covering 
the eye. B, Head of the common Viper (after Bell), showing the poison-fangs. 

curved fangs, one on each maxilla or upper jawbone, which, 
when not in use, are pointed backward, and concealed in a 
fold of the gum, but can be raised at will by special muscles. 
Each tooth is perforated by a fine canal or tube, which opens 
by a distinct aperture at the point of the fang, and is connect¬ 
ed with the duct of the “poison-gland.” This is a gland, 
situated under and behind the eye, secreting the poisonous 
fluid which renders the bites of these snakes dangerous or 
fatal. When the serpent strikes at any animal, the poison is 
forced through the poison-fang into the wound, partly by the 
contractions of the muscular w 7 alls of the gland, and partly by 
the compressive action of the muscles of the jaw r s. In some 
other snakes, several of which are not certainly known to be 



244 


VERTEBRATE ANIMALS. 


venomous, there are large, grooved fangs placed far bach in 
the mouth upon the upper jaw. 

Of the non-venomous, harmless snakes, we have an excel¬ 
lent instance in the common Ringed Snake [Coluber natrix ), 
which is of frequent occurrence in most parts of Europe. 
Like all the snakes, it is strictly carnivorous, having a special 
liking for frogs, which it swallows whole. It often takes to 
the water, and can swim rapidly and gracefully, though, in 
this respect, it is excelled by the true venomous water-snakes 
(.Ilydrophidee ), which are adapted to an aquatic life by having 
a compressed swimming-tail. A well-known American exam¬ 
ple of this group is the common Black Snake (JBascanion 
constrictor). It attains a length of from three to five feet, but 
is perfectly harmless so far as man is concerned. Other non- 
venomous snakes, such as the Boas and Pythons, though des¬ 
titute of poison-fangs, are, nevertheless, highly dangerous and 
destructive animals. Their bite is harmless, and they seize 
their prey by coiling themselves round it in numerous folds. 
By gradually tightening these folds, they reduce their victim 
to the condition of a shapeless bolus, which they finally pro¬ 
ceed to swallow whole. In this way, a large Python or Boa 
will certainly succeed in disposing of an animal as large as a 
sheep or calf, and it has been asserted that human beings, 
and even oxen, can also be swallowed by unusually large 
specimens of this family. 

The Boas and Pythons have a horny spur on each side of 
the vent, and the tail is prehensile. Their dental apparatus is 
extremely powerful, giving them a firm hold for the constric¬ 
tion of their prey. They are the largest of all the serpents, 
attaining a length of thirty to forty feet. The true Boas 
and Anacondas belong to the New World, but the Pythons 
are confined to India, Africa, and the Indian Archipelago. 

The poisonous snakes are represented by the Crotalidce 
of the New World and the Viper idee of the Old World. The 
common Rattlesnake ( Crotalus horridus) of the United States 
has the extremity of the tail furnished with a “ rattle ” or 
horny appendage composed of several membranous cells of a 
pyramidal shape articulated one within the other. Before 
striking its prey, it. throws itself into a coil, and shakes its 
rattle. Another highly-dangerous species is the Copperhead 
( V l 9 onoce phcilus contortrix). The common European viper 
(Pelias berus) is hardly fatal to adults, but its bite causes 
serious inflammation. Highly deadly, however, is the Cobra 
di Capello or Spectacled Snake (JVaja tripudians ) of India, as 


DIVISIONS OF EEFTILIA. 


245 


also is the nearly-allied JVaja haje (Fig. 120) of Africa. Oth¬ 
er venomous snakes of evil notoriety are the Death-adder 
( Acanthophis tortor ) of Australia, the Puff-adder ( Vipera in¬ 
flated) of South Africa, the Horned Viper ( Cerastes cornutus) 
an d the Harlequin-snakes ( Klaps ), but many others 
are equally dangerous. 

Order HI. Lacertilia (Lat. lacerta , a lizard).—The third 
order of reptiles is that of the Lacertilia , comprising all the ani¬ 
mals which are properly known as Lizards, together with some 
snake-like creatures, such as the Blind-worm. They are distin¬ 
guished by the following characters: Usually there are two pairs 
oi well-developed limbs, but there may be only one pair, or all the 
limbs may be rudimentary. In all cases, however, a scapular 
arch is present. The vertebrae are usually hollow in front 
(procoelous), rarely hollow at both ends ( amphiceelous ). In no 
living Lacertilian are the teeth lodged in distinct sockets. 
The eyes are mostly furnished with movable eyelids. 

As a general rule, the animals included under this head 
have four well-developed legs, and would, therefore, be popu¬ 
larly called “ Lizards.” Some of them, however, such as the 
common Blind-worm ( Anguis fragilis) of Europe, exhibit no 
external indications of limbs, and would, therefore, be generally 
regarded as Snakes. These snake-like Lizards, however, can 
be distinguished from the true Ophidians by the consolidation 
of the bones of the head and jaws, and by the fact that the 
eyes are generally provided with movable eyelids. Dissection 
also shows that the shoulder-girdle (or scapular arch) is always 
present in a rudimentary condition. 

Of the snake-like Lizards, a good example is to be found 
in the common Blind-worm or Slow-worm of Europe. It is 
completely serpentiform, without any external indications of 
limbs (Fig. 122), and it is quite harmless. It is remarkable 
for the fact that, when alarmed, it stiffens its muscles to such 
an extent that the tail can readily be broken off, as if it were 
brittle. This same brittleness exists in the Glass-snake ( Ophi- 
saurus ventralis ) of the Southern States, in which also there 
are no limbs. In other allied genera, there may be fore-feet 
alone, or hind-feet may be present, or all four limbs exist in a 
more or less rudimentary condition. In the true Lizards 
(Lacerta), all four limbs are present in a well-developed form; 
as seen in the common Green Lizard ( L. viridis) of Europe. 
The genus Lacerta is represented in America by the Ameivoe , of 
which the Striped Lizard (Ameiva sex-lineata) of the Southern 


246 


VERTEBRATE ANIMALS. 


States may be taken as a good example. Of all living Lizards, 
the largest are the Monitors ( Varanidm ,) which are exclusively 
confined to the Old World, and attain sometimes a length of 
from six to eight feet. Very large, too, are some of the 



Fig. 122.—Blind-worm (Anguis fragilis). (After Bell.) 


Iguanas which occur in warm regions in various parts of 
the world, but especially in South America, where they are 
often eaten. Related to the Iguanas are the singular Lizards 
known as the Flying Dragons (Draco volans ), various species 
of which inhabit the Indian Archipelago and the East Indies. 
They are all of small size, living in trees and feeding on in¬ 
sects ; and their great peculiarity consists in the fact that cer¬ 
tain of the ribs are straightened out, and support a wing-like 
fold of the skin on each side of the body, by means of which 
the animal can take very extensive leaps from tree to tree. 

The Scincoid Lizards form a very large family, represented 
by numerous species in all parts of the world. The species 
figured below is a common form in Egypt and Arabia, and was 
formerly used as a remedy in various diseases. A nearly- 
allied species is the Blue-tailed Lizard (Scincus fasciatus) of 
the United States. 

The Geckos ( Gechotidce ) form a large group of night-lov¬ 
ing Lizards, which are found in most parts of the world, and 


DIVISIONS OF REPTILIA. 


247 


chiefly deserve notice from the fact that their eyes are not pro¬ 
vided with movable eyelids. The Chameleons, also, cannot 
be said to possess movable eyelids, for the eye is covered with 


Fig. 123.—The Skink (Scincus officinalis) 



a single lid, leaving only a central aperture for the pupil. The 
common species (Chameleo Africanus) occurs abundantly in 
the north of Africa, and has long been known for the changes 
of color which it has the power of exhibiting. It is a sluggish 
animal, and catches insects by darting out its long and pro- 
trusible tongue with extreme rapidity. 

Order IV. Crocodilia. —The last and highest order of 
the living Reptiles is that of the Crocodilia , comprising the 
Crocodiles, Alligators, and Gavials, and characterized by the 
following peculiarities: The outer or integumentary skeleton 
consists partly of horny scales developed by the outer layer 
of the skin, and partly of large bony plates produced by the 
inner layer of the skin. The bones of the skull and face are 
firmly united, and the two halves of the lower jaw are joined 
by a distinct suture. The teeth form a single row in both 
jaws, and are implanted in distinct and separate sockets. The 
front ribs of the trunk are double-headed, and there are no 
collar-bones. The heart consists of four distinct chambers, 
two auricles and two ventricles, all completely separated from 


248 


VERTEBRATE ANIMALS. 


one another. The mixture of arterial and venous blood, how¬ 
ever, which is so characteristic of Reptiles, is provided for by 
a communication between the great vessels which spring from 
the two ventricles in the immediate neighborhood of the heart. 
The eyes are protected by movable eyelids, and the ear by a 
movable earlid. The tongue is large and fleshy, and is im¬ 
movably attached to the bottom of the mouth (hence the be¬ 
lief of the ancients that the Crocodile had no tongue). Lastly, 
the Crocodilia agree with the typical Lizards, and differ from 
the Snakes in having four well-developed limbs. 



Fig. 124.— Ilead and fore-part of the body of the common Crocodile {Crocodiles vulgaris). 


The Crocodilia abound in the fresh waters of hot climates, 
and are the largest of all living Reptiles, not uncommonly at¬ 
taining a length of sixteen feet or upward. The best known 
of the Crocodilia is the Nilotic Crocodile, which occurs abun¬ 
dantly in Egypt, and was described by both Herodotus and 
Aristotle. 

The true Crocodiles have the feet’ completely webbed, the 
hind-legs bordered by a fringe, and the fourth tooth in the 
lower jaw received in a notch on the side of the upper jaw. 
They belong mainly to Africa and Asia, but they are also rep¬ 
resented in the West Indies and in South America. 

The Alligators have the hind-legs simply rounded, and the 
toes not completely webbed ; while the fourth tooth in the 
lower jaw fits into a cavity in the palate, and is concealed 
from view when the mouth is shut. Like the Crocodiles they 
are essentially aquatic in their habits, and lie dormant during 
the winter in cold climates and the hot season in warm coun¬ 
tries. They are extremely voracious, and live upon fish and 
small Mammals. The best-known species are the common 
Alligator (A. Mississippiensis) of the Southern States, the 
Caiman (A. palpebrosus ) of Surinam and Guiana, and the 
“ Jacare ” (A. sclerops) of South America. 

The Gavial or Gangetic Crocodile occurs in India, and is 




DIVISIONS OF REPTILIA. 


249 


distinguished by its narrow, elongated jaws, forming a kind 
of beak. It attains a length of more than ten feet. 

Order V. Iciitiiyopterygia (Gr. ichthus , fish; pterux , 
wing).—In this order are included a number of gigantic, fish¬ 
like Reptiles, which are all extinct, and are characteristic of 
the Secondary period of geology, and especially of the forma¬ 
tion known as the Lias. The chief characters by which they 
are distinguished have reference to their purely aquatic life, 
for there can be no doubt that they were inhabitants of the 
sea. Thus the body was fish-like, without any distinct neck. 
The vertebra? were hollow at both ends (amphiccelous ), and 
the spine thus possessed the flexibility and power of motion 
so characteristic of the true fishes. The limbs also consti¬ 
tuted powerful swimming-paddles (Fig. 125), and it is proba¬ 
ble that there was a vertical tail-fin. 

Much has been gathered from various sources as to the 
habits of the Ichthyosauri , and their history is one of the most 
interesting chapters in the geological record. That they 
chiefly kept to open seas may be inferred from their strong 
and well-developed swimming apparatus; but the presence of 
a powerful bony arch supporting the fore-limbs proves that 



Fig. 125 .—Ichthyosaurus communis. 


they must have occasionally betaken themselves to the land. 
That they were tenants of stormy waters, or were in the habit 
of diving in search of prey, has been inferred from the fact 
that the eyeball is protected from pressure by a ring of bony 
plates. That they possessed great powers of vision, espe¬ 
cially in the dusk, seems to be rendered certain from the size 
of the pupil and the enormous width of the bony cavities 
(orbits) which contained the eyes. Lastly, that they were 
carnivorous and predacious in the highest degree is shown bj 
their wide mouths, long jaws, and numerous powerful and 
pointed teeth. This is also proved by an examination of their 
petrified droppings, which are known as “ coprolites,” and 
which contain in abundance undigested fragments of fishes 
and other marine animals. 




250 


VERTEBRATE ANIMALS. 


Order VI. Sauropterygia (Gr. saura , lizard; pterux , 
wing).—The Reptiles belonging to this order agree with the 
last in being all extinct, and in being confined to the Second¬ 
ary period of geology. The best known are the Plesiosauri , 
which resembled the Ichthyosauri in having all the limbs con¬ 
verted into swimming-paddles, but differed in several respects, 
of which the most obvious is the great elongation of the neck 
(Fig. 126). The Plesiosauri were gigantic marine Reptiles, 



chiefly characteristic of the formations known as the Lias and 
Oolites. As regards the habits of the Plesiosaurus , Dr. Cony- 
beare concludes : “ That it was aquatic is evident from the form 
of its paddles; that it was marine is almost equally so from the 
remains with which it is universally associated; that it may 
have occasionally visited the shore, the resemblance of its ex¬ 
tremities to those of the Turtle may lead us to conjecture; its 
movements, however, must have been very awkward on land: 
and its long neck must have impeded its progress through the 
water, presenting a striking contrast to the organization 
which so admirably fits the Ichthyosaurus to cut through the 
waves.” As its breathing-organs are such that it must of ne¬ 
cessity have required to obtain air frequently, it may be in¬ 
ferred “ that it swam upon or near the surface, arching back 
its long neck like a swan, and occasionally darting it down at 
the fish which happened to float within its reach. It may per¬ 
haps have lurked in shoal-water along the coast, concealed 
among the sea-weed, and, raising its nostrils to a level with 
the surface from a considerable depth, may have found a se¬ 
cure retreat from the assaults of powerful enemies; while the 
length and flexibility of its neck may have compensated for 
the want of strength in its jaws and its incapacity for swift 
motion through the water.” 

Order VII. Pterosattria (Gr. pteron , wing; saura , 
lizard).—The Reptiles of this order are all extinct, and, like 
those of the preceding orders, are exclusively confined to the 


DIVISIONS OF REPTILIA. 


251 


Secondary period of geology. The most familiar examples 
are the so-called Pterodactyles , and the distinguishing charac¬ 
ters of the order have reference to the fact that they were all 
adapted for an aerial life. They present, in fact, an extraor¬ 
dinary combination of the characters of birds and reptiles, and 
they make also some approach to the Mammalian order of the 
Bats. In the presence of teeth in distinct sockets, and, as we 
shall see hereafter, in the structure of the fore-limbs, the 
Pterodactyles differ altogether from all known birds; and 
there can be little doubt as to their being genuine Reptiles. 
The only living Reptile which has any power of sustaining 
itself in the air is the little Draco volans , which has been pre¬ 
viously mentioned. In this case, however, the animal has no 
power of true flight, but is simply enabled to take extensive 
leaps by means of a membranous expansion on each side of 
the body. In the Bats, again, the power of genuine flight is 
present; and this is given by means of a leathery membrane 
which is supported chiefly by certain of the fingers—which 
are greatly lengthened—and is attached to the sides of the 
body and hind-limbs. 

In the Pterodactyles the power of true flight was present, 
and this was also conditioned by means of a leathery expand¬ 
ed membrane, attached to the hind-limbs, the sides of the 
body, and the fore-limbs. In this case, however, the chief 
support of the flying membrane was derived from the outer¬ 
most finger of the fore-limb, which was enormously elongated 
(Fig. 127). That the Pterodactyles passed their existence 



Fig. 127 .—Pterodactylus brecirostris, the skeleton and the animal restored. 


chiefly in the air, and did not simply leap from tree to tree, is 
shown by two characters in which they agree with the flying 



252 


VERTEBRATE ANIMALS. 


birds. Many of the bones, namely, were “ pneumatic ”—that 
is to say, were hollow and were filled with air, thus giving the 
animal the degree of lightness necessary for flight. Secondly, 
while the shoulder-girdle has many of the characters of birds, 
the breastbone (sternum) is furnished with a prominent ridge 
or keel, serving for the attachment of the great muscles which 
work the wings. There can be no doubt, therefore, as to the 
Pterodactyles having enjoyed the power of genuine flight. 
Many of them attained no great size, but some of them must 
have been gigantic, the expanse of wing in one species having 
been calculated at probably about twenty-seven feet from tip 
to tip. 

Order VIII. Anomodontia (Gr. anomos , irregular; 
odous , tooth).—This order comprises a few Reptiles which be¬ 
long to the Triassic period of geology, and are distinguished 
by the fact that the jaws were sheathed in horn, so as to form 
a kind of beak very like that of the Turtles. In some species 
there appear to have been no teeth at all; but in one genus 
there were two long tusks, one on each side of the upper jaw. 
The limbs were fitted for walking and not for swimming, and 
these singular Reptiles must, therefore, have been terrestrial 
in their habits. 

Order IX. Deinosauria (Gr. deinos , terrible; saura , 
lizard).—In this order are included a number of extinct Rep¬ 
tiles, most of which were of gigantic size, and which are con¬ 
fined to the Secondary period of geology. They possessed 
teeth, sunk in distinct sockets, and the limbs were extremely 
strong, and adapted for progression on land. In some cases 
the fore-limbs were very much smaller than the hind-limbs, 
and there is reason to suppose that some of these extraordi¬ 
nary animals, though of enormous size, walked habitually 
upon their hind-legs, like Birds. It is also interesting to note 
that the gigantic footprints of the Sandstones of the Connecti¬ 
cut Valley, formerly regarded as formed by Birds, are now 
with great probability looked upon as truly the tracks of Dei- 
nosaurian Reptiles. 


CHAPTER XXIX. 


CLASS IV.—AVES. 

The fourth class of the Vertebrates is that of the Birds or 
Aves, which may be shortly defined as being “oviparous Ver¬ 
tebrates, with warm blood, a double circulation, and a cover¬ 
ing of feathers ” (Owen). The other leading characters which 
separate the Birds from the other Vertebrata are that the red 
blood-corpuscles are nucleated, the skull articulates with the 
spine by a single articulating surface (or condyle), the breath¬ 
ing-organs are in the form of lungs, which communicate with 
a variable number of air-sacs scattered through the body, and 
the fore-limbs are never terminated (in existing birds) by more 
than two fingers, ending in claws, and are generally modified 
so as to form “ wings ” or organs of flight. 

The feathers, which form such a distinctive character of 
birds, are formed by a modification of the outer layer of the 
skin (epidermis), and from their non-conducting nature they 
serve to maintain the high temperature of the body which is 
so characteristic of the class. A typical feather, such as one 
of the long feathers of the tail or wing, consists of the follow¬ 
ing parts: 1. A horny cylindrical tube, which forms the lowest 
portion of the feather, and is termed the “quill.” 2. The 
“ shaft,” which forms the central axis of the feather, and which 
is simply the continuation of the “ quill.” The under surface 
of the shaft is always marked by a strong longitudinal groove, 
and it consists of a horny sheath, filled with a white spongy 
material, not unlike the pith of a plant. 3. The “ webs,” which 
form the lateral expansions of the feather, and are attached 
to the sides of the shaft. Each web is composed of a number 
of small branches, called the “ barbs,” and each barb, in turn, 
is furnished with a series of smaller fibres called the “ bar- 
bules.” As a rule, the barbs are all kept in connection with 


254 


VERTEBRATE ANIMALS. 


one another by means of the barbules, the ends of which are 
hooked. Toward the base of the shaft, however, the barbs 
are usually more or less separate and placed at a distance from 
one another, constituting what is known as the “ down.” In 
the Ostriches and the birds allied to them, all the barbs are 
disunited and placed at a distance, and they are often not at 
all unlike hairs in appearance. The feathers of birds not only 
greatly conduce to the high temperature of the body, but also 
serve to keep out moisture, to which end there is a peculiar 
oil-gland at the base of the tail, with the secretion of which 
the bird anoints its plumage. 

The skeleton of birds exhibits many points of peculiar 
interest, mostly in adaptation to an aerial mode of life; but 
only some of the more important of these can be noticed here. 
The entire skeleton is at the same time peculiarly compact 
and singularly light, the compactness being due to the pres¬ 
ence of an unusual quantity of phosphate of lime, and the 
lightness to the fact that many of the bones are filled with air 
in place of marrow. The cervical region (neck) of the verte¬ 
bral column is unusually long and flexible, since the fore-limbs 
are useless as organs of prehension, and all these functions 
have to be performed by the beak. In all birds the neck is, at 
any rate, sufficiently long to allow of the application of the 
beak to the tail, so as to permit of the cleaning and oiling of 
the whole plumage. The vertebrae which form the back or 
dorsal region of the spine are generally more or less immov¬ 
ably connected together, so as to give a base of resistance to 
the wings. In the Ostrich, however, and in other birds in 
which the power of flight is either very limited or is absent, 
the dorsal vertebrae are more or less movable one upon the 
other. The vertebrae which follow the dorsal region of the 
spine are all amalgamated together to form a single bony 
mass, which is termed the “sacrum,” and this, in turn, is 
united on both sides with the bones which form the pelvic 
arch, which carries the hind-limbs. The vertebrae of the tail 
are more or less movable upon one another; and in almost all 
living birds, when fully grown, the last joint of the tail (Fig. 
129, B, s) is a long, slender, ploughshare-shaped bone, which 
is really composed of several vertebrae united together. It is 
usually set on at an angle nearly perpendicular to the axis of 
the body, and it serves to support the great tail-feathers, 
which act as a rudder during flight. It also serves to support 
the oil-gland, which supplies the secretion with which the 
feathers are lubricated. The skull in birds has its several 


AYES. 


255 


bones generally so amalgamated in the adult, that it forms a 
bony case of a single piece, the lower jaw alone remaining 
movable. The head is jointed to the spine by no more than 
a single articulating surface or condyle. The beak, which 
forms such a conspicuous feature in birds, is composed of two 
halves, an upper half or “upper mandible,” and a “lower 
mandible.” The lower mandible, like the lower jaw of all the 
Sauropsida , is at first composed of several pieces, but these 
are all undistinguishably united in the adult, and the two 
halves of the jaw are also amalgamated together. In ho adult 
bird are teeth ever developed in either mandible; but both 
mandibles are sheathed in horn, constituting the “ beck,” end 
the margins of this sheath are sometimes serrated. 

The most characteristic points, however, in the skeleton of 
the birds, are to be found in the structure of the limbs. The 
cavity of the chest or thorax is bounded behind by the dorsal 
vertebras, on the sides by the ribs, and in front by the breast¬ 
bone or sternum. The ribs vary in number from seven to 
eleven pairs, and in most birds each rib gives off a peculiar 
process (Fig. 128, B), which passes over the rib next in suc¬ 
cession behind. In front the ribs are jointed to a series of 
straight bones, which are called the “ sternal ribs,” and these, 
in turn, are movably articulated to the breastbone in front. 
According to Owen, these sternal ribs are “ the centres upon 
which the respiratory movements hinge.” In front the cavity 
of the chest is completed by an enormously-expanded breast¬ 
bone or sternum (Fig. 128, A), 'which, in most birds of any 
powers of flight, extends more or less over the abdominal 
cavity as well. The sternum of all birds which possess the 
power of flight is characterized by the presence of a prominent 
ridge or “keel” (Fig. 128, A, b), to which are attached the 
great muscles (pectoral muscles) which move the wings. As 
a general rule, the size of this crest or keel gives a tolerably 
just estimate of the flying powers of the bird to which it be¬ 
longed. The keel is, of course, most largely developed in 
those birds which possess the powder of flight in its greatest 
perfection; and in those which do not fly, such as the Ostrich, 
there is no sternal keel at all. The pectoral arch or shoulder- 
girdle of birds consists of the shoulder-blades (scapula?), the 
clavicles or collar-bones, and of two bones, which are distinct 
in birds, and are called the “ coracoid bones.” The shoulder- 
blades (s s) are usually long and narrow bones. The coracoid 
bones (kk) correspond with the part of the shoulder-blade 
which is known in most of the Mammals as the “coracoid 


256 


VERTEBRATE ANIMALS. 



Fia. 128.—A, Breastbone, shoulder-girdle, and fore-limb of Penguin (after Owen); b Breast¬ 
bone (sternum), with its prominent ridge or keel; s s Shoulder-blades (scapulae ); Tc k 
Coracoid bones; c Furculum or Merry-thought, composed of the united collar-bones 
(clavicles ); h Bone of the upper arm or humerus ; r Radius; u TJlna, forming together 
the forearm; q Bones of the wrist or carpus; t Thumb; m Metacarpus; p Phalanges 
of the fingers. B,'Ribs of the Golden Eagle; a a Ribs giving off processes (b 6); cc 
Sternal ribs. 


process; ” and in birds they are not only separate bones, but 
they are the strongest bones of the pectoral arch. They are 
more or less nearly vertical, and they form fixed points for 
the downward stroke of the wing. The collar-bones or clavi¬ 
cles (c) in the great majority of birds are united together in 
front, so as to form a somewhat V-shaped bone, which is tech¬ 
nically called the “furculum,” but is familiarly called the 
“ merry-thought.” The function of this clavicular arch is to 
keep the wings asunder during their downward stroke, and 
the strength of the furculum varies, therefore, with the powers 
of flight enjoyed by each bird. The bones which form the 
limb proper, or “ wing,” are considerably modified to suit the 
special function of flight, but essentially the same parts are 
present as in the fore-limb of the Mammals. The upper arm 
is constituted by a single bone, the humerus (7i), which is gen¬ 
erally short and stout. The forearm is composed of two 
bones, the radius (r) and the ulna (u), of which the ulna is 
the bigger. These are followed by the small bones, which 







AYES. 


257 


form the wrist or carpus (q), but these are reduced to two in 
number. The carpus is followed by the bones which con¬ 
stitute the root of the hand or metacarpus (m), but these are 
also reduced to two , instead of being live in number, as they 
are in most Mammals. The two metacarpal bones are also 
amalgamated together at both ends, so as to form a single 
piece, at the base of which, on its outer side, is a rudimentary 
digit, the “thumb” (£), which carries a tuft of feathers,known 
as the “ bastard wing.” The metacarpal bones, finally, sup¬ 
port each a single finger (/>), of which one is never composed 
of more than one bone or phalanx , while the other is com¬ 
posed of two or three phalanges. (To understand thoroughly 
the leading modifications of the limbs of birds, the student 
will do well to refer to the general description of the limbs of 
Vertebrates, p. 200, Figs. 96, 97.) 

As regards the composition of the hind-limb in birds, the 
two halves of the pelvic arch (i. e., the innominate bones) al- 



Fig 129 --A Pelvis and bones of the Leg of the Loon or Diver (after Owen): i Innominate 
bone- f Thigh-bone (femur); t Tibia, r fibula, together forming the shank; m Tarso- 
metatarsus; p Phalanges of the toes. B, Tail of the Golden Eagle; s Ploughshare- 
shaped bone, carrying the great tail-feathers. 





258 


VERTEBRATE ANIMALS. 


ways form a single piece each, and they are always fiimly 
united with the sacral region of the spine. With the single 
exception, however, of the Ostrich, they do not unite below, 
but remain separate. As in the higher Vertebrates, the lower 
limb consists of a thigh-bone ( < femur ), a shank, composed of 
two bones {tibia and fibula), a tarsus, a metatarsus, and pha¬ 
langes, but some of these parts are obscured by coalescence. 
The thigh-bone or femur (Fig. 129, f) is generally very short, 
comparatively speaking; and the chief bone of the leg is the 
tibia ( t ), to which a thin and tapering fibula ( r ) is attached. 
In the regular typical limb of a Vertebrate animal the tibia 
and fibula would be followed by a series of small bones, called 
the tarsus , constituting the ankle-joint (Fig. 97); and the tar¬ 
sus would in turn be followed by a series of bones constituting 
the root of the foot, or metatarsus. In Birds, however, the 
tibia and fibula are followed by a single cylindrical bone, 
which is called the “ tarso-metatarsus ” ( m ), and which is 
formed by the amalgamation of the entire metatarsus with the 
whole or a portion of the tarsus. The most probable view is 
that only the lower portion of the tarsus is present in the 
tarso-metatarsus, and that the upper portion of the tarsus is 
fused with the lower end of the tibia. In this case the ankle- 
joint is placed in the middle of the tarsus. The tarso-meta- 
tarsus is followed below by the foot, which consists in most 
birds of four toes, of which three are directed forward and 
one backward. In no wild birds are there more than fcur 
toes; but some domesticated varieties possess a fifth. In 
most birds with four toes, the toe which is directed backward 
consists of two phalanges; the innermost of the three forwaid 
toes has three phalanges, the next has four, and the outer¬ 
most toe is composed of five. In many birds, such as the 
Parrots, the outermost toe is turned backward, so that there 
are two toes in front and tw T o behind. In the Swifts, again, 
all the four toes are turned forward. In many of the swim¬ 
ming-birds ( Natatores ) the hinder toe is wanting or rudimen¬ 
tary ; and in the Ostrich both this and the next toe are ab¬ 
sent, so that the foot consists of no more than two toes. 

The digestive system in Birds consists of the beak, tongue, 
gullet, stomach, intestine, and cloaca, with certain accessory 
glands. There are no teeth, and the beak is employed, in dif¬ 
ferent birds, for holding and tearing the prey, for prehension, 
for climbing, and in some cases as an organ of touch, being in 
these last instances more or less soft, and supplied with 
nervous filaments. In many birds, too, the base of the bill is 


AYES. 


259 


surrounded by a circle of naked skin, constituting what is 
called the “ cere,” and this, too, serves as an organ of touch. 
The tongue of birds can rarely be looked upon as an organ of 
taste, since it is generally cased in horn, like the mandibles. 
It is principally employed as an organ of prehension, but it is 
soft and fleshy in the Parrots, and in them, doubtless, acts as 
an organ of taste. Salivary glands are always present, but 
they are rarely of large size, and are often of extremely simple 
structure. In accordance with the length of the neck, the 
gullet is usually very long in birds, and is generally very di¬ 
latable. In the flesh-eating and grain-eating birds the gullet 
is dilated (Fig. 130, c) into a pouch which is called the 



Fig. 130. —Digestive System of the common Fowl (after Owen), o Gullet; c Crop; p Pro- 
ventriculus, g Gizzard; sm Small intestine; Jc Intestinal cseca; l Large intestine; 
cl Cloaca. 

“ crop,” and is situated in the lower part of the neck, just in 
front of the merry-thought. This may be simply a dilatation 
of the tube of the gullet, or it may be a single or double 
pouch. The function of the crop is to detain the food, for a 
longer or shorter period, according to its nature, before it is 
submitted to the action of the proper digestive organs. In the 
Pigeons, the food which has been previously softened in the 



260 


VERTEBRATE ANIMALS. 


crop is returned to the mouth, and supplied to the young in a 
state suitable for digestion. The gullet, after leaving the 
crop, shortly opens into a second cavity, called the “ proven- 
triculus,” which is the true digesting stomach, and is richly 
supplied with glands which secrete the digestive fluid or gas¬ 
tric juice (p). This, in turn, opens into a muscular cavity 
which is called the “gizzard” (<?), and which leads into the 
commencement of the small intestine. The characters of the 
gizzard vary with the nature of the food. In the birds of 
prey, which live on a easily-digested animal diet, the walls of 
the gizzard are thin and membranous. In the grain-eating 
birds, such as the fowls, whose hard food requires to be 
crushed before it can be properly digested, the walls of the 
gizzard are extremely thick and muscular, and the inner lin¬ 
ing is hard and horny. In these birds the gizzard constitutes 
a kind of grinding apparatus, like the stones of a mill; while 
the “ crop ” may be compared to the “ hopper ” of the mill, 
since it supplies to the gizzard “ small successive quantities 
of food as it is wanted (Owen). The grinding action of the 
gizzard is further assisted by the small pebbles and gravel 
which, as is well known, so many birds are in the habit of 
swallowing. These pebbles take the place of teeth, and there 
can be no doubt that they are in many cases essential to 
health, the bird being otherwise unable to triturate its food 
properly. The intestinal canal extends from the gizzard to 
the cloaca (cQ, and is comparatively short. The secretions of 
the liver and pancreas are poured into the commencement of 
the small intestine. The commencement of the large intestine 
is furnished in most birds with two blind tubes or caeca ( k ). 
These vary considerably in length in different birds, and are 
sometimes wanting; while their exact function is still ques¬ 
tionable. The large intestine is seldom more than a tenth 
part of the length of the body, and is generally conducted 
straight from the caeca to the cloaca. The cloaca is a com¬ 
mon cavity which in birds, as in Reptiles, receives the termi¬ 
nation of the intestine and the ducts of the generative and 
urinary organs (cl). 

Respiration is effected in Birds more completely, exten¬ 
sively, and actively, than in any other class of the Vertebrata , 
and, as the result of this, their average temperature is higher 
than in any other Vertebrates. This extensive development 
of the respiratory process is due to the fact that air is admit¬ 
ted in Birds not only to the lungs, but also to the interior of 
a greater or less number of the bones, and to a series of air- 


AVES. 


261 


receptacles which are scattered through various parts of the 
body. The lungs are two in number, of a bright-red color, 
and spongy texture, and they are confined to the back part 
of the chest. They differ from the lungs of Mammals in not 
being freely suspended in a membranous bag {pleura), but in 
being fixed to the back wall of the chest. The thoracic and 
abdominal cavities are not separated from one another by a 
complete partition (midriff or diaphragm) as the Mammals, but 
the common thoracico-abdominal cavity is subdivided by means 
of membranous partitions into a series of cavities or sacs, which 
are termed the “air-receptacles.” These air-sacs are filled 
with air from the lungs, and vary considerably in number and 
size in different birds. They not only serve greatly to reduce 
the specific gravity of the body, but also assist largely in the 
aeration of the blood. Connected with the air-receptacles, 
and supplementing their action in both of these respects, is a 
series of cavities occupying the interior of a greater or less 
number of the bones, and also containing air. In young birds 
these air-cavities in the bones do not exist, and the bones are 
simply filled with marrow, as in the Mammals. In the Pen¬ 
guin, which does not fly, none of the bones contain air-cavities 
or are “pneumatic;” and in the Ostrich only a few of the 
bones contain air. In the Pelican and Gannet all the bones 
of the skeleton, except the phalanges of the toes, are per¬ 
meated by air; and in the Hornbill even these are pneu¬ 
matic. 

The heart in all birds consists of four chambers, and the 
two sides of the heart are completely separated from one 
another. In all essential details, as regards the structure of 
the heart and great vessels, and the course of the circulating 
fluid, Birds agree with Mammals. The impure venous blood 
which has traversed the body is returned by the great veins 
to the right auricle. From the right auricle it passes into the 
right ventricle, from which it is driven by the pulmonary artery 
to the lungs. Having been submitted to the action of the air 
contained in the lungs, and having been thereby changed into 
arterial blood, the blood is sent back to the left auricle by 
means of the pulmonary veins. Thence it passes into the 
left ventricle, by which it is again propelled throughout the 
whole body, to return again as venous blood to the right side 
of the heart. The heart, therefore, of birds, differs from that 
of reptiles in consisting of two sides, each composed of an 
auricle and ventricle, the right side being wdiolly concerned 
with sending the venous blood to the lungs, and the left side 


262 


VERTEBRATE ANIMALS. 


being entirely occupied with sending the arterial blood to the 
body. The right side of the heart is therefore venous, the left 
side arterial. In all Reptiles, on the other hand, the two cir¬ 
culations—namely, that through the lungs and that through 
the body—communicate with one another, either in the heart 
itself or in its immediate neighborhood; so that both the lungs 
and the body are supplied with a mixture of venous with arte¬ 
rial blood. Though the heart of Birds resembles that of Mam¬ 
mals in general structure, its cavities are “ relatively stronger, 
their valvular mechanism is more perfect, and the contractions 
of this organ are more forcible and frequent in Birds, in ac¬ 
cordance with their more extended respiration and their more 
energetic muscular actions” (Owen). The urinary organs of 
birds consists of two elongated kidneys, which open by means 
of their ducts (the ureters) into the cloaca, along with the ter¬ 
mination of the intestine and the ducts of the reproductive 
organs. As a general rule, the female bird is provided with 
only a single ovary—that of the left side—and all birds, with¬ 
out exception, are oviparous. The egg is always enclosed in 
a calcareous shell, and is developed after expulsion from the 
body, by the process of “incubation” or “brooding”—a pro¬ 
cess for which birds are especially adapted, in consequence of 
their very high average temperature. The young bird, when 
ready for an independent existence, perforates the shell, often 
by means of a temporary calcareous excrescence developed 
upon the point of the upper mandible of the bill. In some 
birds, mostly in the case of those which live upon the ground, 
the young are able to run about and look for food directly 
after they come out of the egg, as is seen in the common 
Fowl. In most birds, however, the young are liberated from 
the egg in a perfectly helpless and naked condition, and re¬ 
quire to be fed by their parents for a longer or shorter time, 
before they are able to take care of themselves. Most of these 
birds, such as our common song-birds, reside in trees, and 
build more or less elaborate nests. 

As regards their nervous system , the brain of Birds is rela¬ 
tively larger than the brain of Reptiles, but it is destitute of 
those folds or convolutions which form so marked a feature in 
the brain of most Mammals. The organs of sense, with the 
exception of touch and taste, are well developed in Birds, 
vision especially being generally extremely acute. The eyes 
are always well developed, and in no bird are they ever want¬ 
ing or rudimentary. The chief peculiarity of the eye of Birds 
is, that its anterior portion ( cornea ) forms the segment of a 


AYES. 


263 


much smaller circle than does the eyeball proper; so that the 
whole eye assumes a conical shape. Another peculiarity is 
that the form of the eye is maintained by means of a circle of 
from thirteen to twenty bony plates, which are placed in the 
front portion of the fibrous coat of the eye {sclerotic). Eye¬ 
lashes are almost universally absent; but, in addition to the 
ordinary upper and lower eyelids, Birds possess a third mem¬ 
branous eyelid—the membrana nictitans —which is placed on 
the inner side of the eye. This nictitating membrane is some¬ 
times transparent, sometimes pearly white, and it can be drawn 
over the front of the eye like a curtain, moderating the too 
great intensity of the light. As regards the organ of hearing, 
the chief point to remark is that Birds have mostly no external 
ear, by means of which the undulations of sound can be col¬ 
lected and transmitted to the internal ear. In some birds, 
however, as the Ostrich, the external opening af the organ 
of hearing is provided with a circle of feathers, which can be 
raised and depressed at will. In the nocturnal Birds, also, 
(such as Owls), the external opening of the ear is protected 
by a musculo-membranous valve, foreshadowing the gristly 
external ear of Mammals. The sense of smell is apparently 
seldom very acute in Birds, and even the Birds of Prey appear 
to seek their food mainly by the sight. The external nostrils 
are usually placed on the sides of the upper mandible, near its 
base, and form simple perforations which sometimes communi¬ 
cate from side to side. In the curious Apteryx of New Zea¬ 
land, the nostrils are placed at the extreme end of the elon¬ 
gated beak. Sometimes the nostrils are defended by bristles, 
and sometimes by a cartilaginous scale. 

Before passing on to a consideration of the divisions of 
Birds, a few words may be said on the migrations of Birds. 
In temperate and cold climates, few birds remain constantly in 
the same region in which they were originally hatched. Those 
which do so are called “ permanent birds.” Other birds, such 
as the Woodpeckers, migrate from place to place without fol¬ 
lowing any very definite course. These are called “ wander¬ 
ing birds,” and their movements are chiefly conditioned by the 
scarcity or abundance of food in any particular locality. Other 
birds, however, at certain seasons of the year, undertake long 
journeys, usually uniting for this purpose into larger or smaller 
flocks. Such birds—of which the Swallows are a familiar in¬ 
stance—are properly called “ migratory birds,” and their move¬ 
ments are conditioned by the necessity of having a certain 
average temperature, without which they cannot live. Thus 


264 


VERTEBRATE ANIMALS. 


the migratory birds of cold climates, when the cold season 
comes on, travel to warmer countries ; but when the hot sea¬ 
son of these regions approaches, they migrate back again to 
temperate zones. 



CHAPTER XXX. 


DIVISIONS OF BIRDS. 

Birds may be variously divided, but for our present pur¬ 
pose it is most convenient to regard them as divided into the 
following eight orders: 

I. Natatores or Swimming Birds , characterized by having 
the feet webbed, and the legs short and placed far back, while 
the body is closely covered with feathers and with a thick 
coating of down next the skin. (Ex. Ducks, Geese, Pelicans.) 

II. Grallatores or Wading Birds , characterized by having 
very long legs, which are destitute of feathers from the lower 
end of the tibia downward. The toes are usually long and 
straight, and are never connected to one another by membrane. 
(Ex. Curlews, Snipes, Herons, Storks.) 

III. Cur sores or Running Birds , characterized by having 
very short wings, which are not used in flight; the breast¬ 
bone is without a ridge or keel; the legs are very robust; and 
the hind-toe is wanting or rudimentary. (Ex. Ostriches and 
Emeus.) 

IV. Basores or Scratching Birds , characterized by usually 
having strong feet, with powerful blunt claws, used for scratch¬ 
ing. The upper mandible of the bill is strongly curved and 
vaulted, and the nostrils are pierced in a membranous space 
at its base, and are covered by a cartilaginous scale. (Ex. 
Fowls, Pheasants, Pigeons.) 

V. Scansores or Climbing Birds , characterized by having 
a climbing foot, in which two toes are turned backward and 
two forward. (Ex. Woodpeckers, Parrots, Cuckoos.) 

VI. Insessores or Perching Birds , characterized by having 
short and slender legs, with three toes in front and one be¬ 
hind, the whole foot being adapted for perching. (Ex. Larks, 
Linnets, Swallows, Crows, Humming-birds.) 



Fig. 131.—Natatores. Penguin (Spheniscns demersus)- 


266 VERTEBRATE ANIMALS. 


VII. II apt ores or Birds of Prey , characterized by having 
a strong, sharp-edged, and sharp-pointed beak, adapted for 
tearing animal food, and by their robust legs, armed with four 
toes, three in front and one behind, all of which are furnished 
with long, strong, crooked claws or talons. (Me. Eagles, 
Hawks, Owls.) 

VIII. jS aururae or Lizard-tailed Birds , characterized by 
having a tail longer than the body, composed of numerous 
distinct and movable vertebrae, each of which carries a single 
pair of quill-feathers. (This order includes only the remark¬ 
able fossil bird, the Archaeopteryx .) 


Order I. Natatores (Lat. natator , a swimmer).—The 
order of the Swimming Birds comprises birds which are as 
much at home in the water as upon land, or even more so. In 
accordance with their aquatic mode of life, the Matatores have 
a boat-shaped body, generally elongated, and usually having a 
long neck. The legs are short, and are placed behind the cen- 




DIVISIONS OF BIRDS. 


267 


tre of gravity of the body; this position enabling them to act 
admirably as swimming-paddles, at the same time that it ren¬ 
ders the gait upon dry land comparatively awkward and shuf¬ 
fling. The toes in all the Natatores are webbed to a greater 
or less extent, or, in other words, are united by a membrane 
(Fig. 131). In many the web or membrane between the toes 
is stretched completely from toe to toe, but in others the mem¬ 
brane is divided between the toes, so that the feet are only 
imperfectly webbed. As their aquatic mode of life exposes 
them to great reductions of temperature, the body in the Na¬ 
tatorial birds is closely covered with feathers, with a thick 
covering of down next the skin. They are further protected 
against becoming wet while in the water by the great develop¬ 
ment of the oil-gland at the tail, by means of which the dense 
plumage is kept constantly oiled. As a rule, the Natatorial 
birds are polygamous, each male having several females; and 
the young are hatched in a condition not requiring assistance 
from their parents, being able to swim about and procure food 
for themselves the instant they are liberated from the egg. 

Among the more important families of the Natatores may 
be enumerated the Penguins (/Sphe?iiscidce ), the Auks ( Al - 
cidai){ the Gulls and Terns ( Laridce ), the Petrels ( Procella - 
ridee ), the Pelicans (. Pelicanus ), the Cormorants {JPhalacro- 
corax ), the Gannets ( Sula ), the Ducks ( Anatidce ), the Geese 
(Anserince), and the Swans ( Cygnidce). 

The Penguins and Auks, with their allies the Divers, Guil¬ 
lemots, and Grebes, have rudimentary, or at any rate small, 
wings, and are all more at home in the water than upon land. 
The Gulls, Terns, and Petrels, on the contrary, are all birds of 
powerful flight, and some of them, such as the Albatross, are 
habitually found hundreds of miles from the nearest land. 
The Pelicans, with their allies the Cormorants, Frigate-birds, 
and Darters, are excellent flyers, and also not uncommonly 
perch on trees, which few Natatorial birds do. They are dis¬ 
tinguished by having the hinder toe directed inward, and 
united to the innermost of the front toes by a continuous 
membrane. The Gannets, Ducks, Geese, and Swans, have the 
bill very much flattened and covered by a soft skin. The 
edges of the bill are also furnished wdth a series of transverse 
plates, which form a kind of fringe or “strainer,” by means 
of which these birds sift the mud in w T hich they habitually 
seek their food. 

Order II. Grallatores (Lat. gralloe, stilts).—The Wading 
Birds for the most part frequent moist situations, such as 


268 


VERTEBRATE ANIMALS. 


marshes and shallow ponds, the shore of the sea, or the banks 
of rivers or lakes, though some of them keep entirely, or al¬ 
most entirely, to the dry land. In accordance with their semi- 
aquatic, amphibious habits, the Waders are distinguished by 
the great length of their legs—the increase in length being 
chiefly due to the elongation of the tarso-metatarsus. The 
legs (Fig. 132) are also unfeathered or naked, as far as the 



lower end of the tibia, at any rate. There are three anterior 
toes, and usually a short hind-toe; but the toes are never com¬ 
pletely webbed, though they are sometimes partially palmate. 
The wings are long, and the power of flight is usually consid¬ 
erable ; but the tail is very short, and its function as a rudder 
is chiefly transferred to the long legs, which are stretched out 
behind in flight. The beak is almost always of great length, 
generally longer than the head (Fig. 132), and usually more or 
less pointed, though it is sometimes flattened. In the Avocet 
the bill is curved upward, instead of being straight, or bent 
downward, as is generally the case. The typical Waders, as 
before said, spend most of their time wading about in shallow 




DIVISIONS OF BIRDS. 


269 


water, feeding upon small fishes, shell-fish, worms, and insects. 
Others, such as the Storks, live mostly upon the land, and are 
more or less exclusively vegetable-feeders. 

Among the more important Grallatorial birds are the Rails 
(Rallidce), Water-hens ( Gallinulce ), Cranes ( Gruidce), Herons 
( Ardeidce ), Storks ( Giconince ), Snipes ( Scolopacidce ), Sand¬ 
pipers ( Tringidae ), Curlews (Numenius) , Plovers ( Charadrii- 
dce ), and Bustards ( Otidce ). 

The Rails are more or less terrestrial in their habits, but 
inhabit marshes and fens. Good examples are the Marsh 
Hen (Rallus elegans) and the Virginia Rail (R. Virginianus) 
of North America, and the Corn Crake ( Crex pratensis) of 
Europe. The Water-hens ( Gallinula ) and Coots (Fulica) are 
aquatic or semi-aquatic, swimming and diving with the great¬ 
est ease. The Cranes are in the main vegetable-feeders, and 
inhabit dry plains. The Herons, Egrets, Bitterns, and Night 
Herons, form a beautiful family of wading birds, represented 
in almost every portion of the known world. Nearly allied to 
these are the brilliantly-colored Ibises ( Tantalince ), which 
inhabit all warm countries. The Giconince are all large birds, 
and comprise the Storks and Adjutant, while the Spoon¬ 
bills are mainly separated from them by their flattened, spoon¬ 
shaped bill. The Scolopacidce , comprising the Snipes and 
Woodcocks, the Tringidce (or Sandpipers), the Curlews (Nu- 
menius ), and various other allied birds, are distinguished from 
the preceding by the possession of a long, soft, slender bill, 
which is used in probing the ground for food. In the Chara- 
driidce are comprised the Oyster-catchers, Turnstones, Lap¬ 
wings, Plovers, Thick-knee, and many other familiar birds. 
Lastly, the Otidoe comprise only the Bustards, which are ex¬ 
clusively confined to the Old World, and make a decided ap¬ 
proach to the Cursorial Birds. 

Order III. Cursores (Lat. curro , I run).—The Running 
or Cursorial Birds, comprising the Ostrich, Cassowary, Emeu, 
Rhea, and Apteryx, are characterized by the rudimentary con¬ 
dition of the wings, which are useless as organs of flight, and 
by the compensating length and strength of the legs. In ac¬ 
cordance with this condition of the limbs, the bones have few 
air-cells, and the breast-bone is destitute of the prominent 
ridge or keel to which the great muscles of the wings are at¬ 
tached. The two sides of the pelvis are united together below 
in the Ostrich, and in all the pelvic arch has great strength 
and stability. The legs are extremely powerful, and the hinder 


270 


VERTEBRATE ANIMALS. 


toe is wanting in all except the Apteryx , in which it is present 
in a rudimentary condition. The front toes (Fig. 133) are 
either two or three in number, and are furnished with strong 
blunt claws or nails. The feathers present the remarkable 
peculiarity, that the barbs, instead of being connected by 
means of the barbules, are disconnected and separate from 
one another, thus coming to resemble hairs in appearance. 



Fig. 183.—Cursores. The Apteryx Australis (Gould). 


The African Ostrich (Struthio camelus ), which is one of 
the best-known members of this order, inhabits the desert 
plains of Africa and Arabia, and is the largest of living birds, 
attaining a height of from six to eight feet. The head and 
neck are nearly naked, and the quill-feathers of the wings and 
tail have their barbs wholly separate, constituting the ostrich- 
plumes of commerce. The legs are extremely strong, and the 
feet have only two toes each. The Ostriches run with extraor¬ 
dinary speed, and can outstrip the fastest horse. They are 
polygamous, each male having several females, and they keep 
together in larger or smaller flocks. The American Ostriches 
or Rheas are much smaller than the African Ostrich, and have 
the head feathered, while the feet are furnished with three 
toes each. They inhabit the great plains of South America, 
and are polygamous. The Emeu ( Dromaius ) is exclusively 
confined to New Holland. In size it nearl}* equals the African 


DIVISIONS OF BIRDS. 


271 


Ostrich, standing from five to seven feet in height, and it is 
not uncommonly kept as a domestic pet. The Cassowary 
(Casuarius galeatus) inhabits the Moluccan Islands and New 
Guinea, and was first brought alive to Europe by the Dutch. 
It stands about five feet in height, and possesses a singular 
horny crest upon the head. Another species of Cassowary in¬ 
habits Australia, and other species are known to exist in the 
Indian Archipelago. The last of the living Cursorial birds is 
the curious bird, the Apteryx (Fig. 133) of New Zealand. In 
this remarkable bird the beak is extremely long and slender, 
and the nostrils are placed at the extremity of the upper man¬ 
dible. The legs are comparatively short, and there is a rudi¬ 
mentary hind-toe, provided with a claw. The feathers of the 
general plumage are long and hair-like, and the wings are 
altogether rudimentary. 

Order IV. Rasores (Lat. rado , I scratch).—The Scratch¬ 
ing Birds—or, as they are often called, the Gallinaceous Birds 
—are characterized by the fact that the upper mandible of the 
bill is convex and vaulted (Fig. 134), and has a membranous 
space at its base, in which the nostrils are pierced. The nos¬ 
trils are also covered by a cartilaginous scale. The legs are 
strong and muscular, and are often covered with feathers as 
far as the ankle-joint. There are four toes (Fig. 134), three 
in front, and a short hind-toe placed on a higher level than the 
others. All the toes, in the typical members of the order, are 
provided with strong, blunt claws, suitable for scratching. 
The food of the Rasores consists chiefly of hard grains and 
seeds, and, in accordance with this, they have a large crop, 
and an extremely strong and muscular gizzard. They gener¬ 
ally lay their eggs upon the ground, and they are mostly 
polygamous, each male having several mates. The Doves, 
however, pair for life. The males take no part in building 
the nest or in hatching the eggs; and the young are generally 
precocious, being able to run about and provide themselves 
with food from the moment they quit the egg. The wings 
are usually weak, and the flight feeble, and accompanied with 
a whirring sound; but many of the Pigeons are powerful 
flyers. 

The order Rasores is divided into two very well marked 
sections or sub-orders, called respectively the Gallinacei and 
Golumbacei. In the Gallinacei are all the typical forms of 
the order, and the characters of this section are therefore the 
same as those of the order itself. They are distinguished from 


272 


VERTEBRATE ANIMALS. 


the Columbacei mainly by being less fully adapted for flight, 
their bodies being much heavier, comparatively speaking, their 
legs and feet stronger, and their wings shorter. They are also 
generally polygamous, and the males usually possess “ spurs,” 
and are more brilliantly colored than the females. 



Fig. 134.—Easores. Eock-pigeon (Colvmba lima). 


The leading families of the Gallinaceous birds are: 1. The 
Tetrcionidce or Grouse family, comprising the true Grouse and 
Black Game (Tetrao), the Ptarmigans (Lagopus), the Ruffed 
Grouse (Bonasa), etc. 2. The Perdicidm or Partridge family, 
comprising the Partridges ( Perdix ), Quails ( Coturnix), Vir¬ 
ginian and Mountain Quails ( Ortyx), Crested Quails (Lophor- 
tyx ), etc. 3. The Phasianidce, or Pheasant family, comprising 
the various Pheasants ( Phasianus ), the Domestic and Jungle 
fowls (Gallus), the Turkeys (Meleagris), the Guinea-fowls 
(JTumida), and the Pea-fowl (Pavo). 4. The Megapodidoe, 
or Mound-builders, comprising only some singular Australian 
and Indian birds, which build enormous mounds, in which they 
deposit their eggs. 5. The CracidcB, or Curassow family, 


DIVISIONS OF BIRDS. *13 

comprising the large South and Central American birds known 
as Curassows and Guans. 

The Columbacei comprise the Pigeons and Doves (Fig. 134), 
and they are separated from the typical llasores by being 
much more fully adapted for flight. They are furnished with 
strong wings and are good flyers ; and, in place of being ground- 
birds, their habits are to a great extent arboreal, in accordance 
with which the feet are slender and are adapted for perching. 
They are also not polygamous, and their voice is of a much 
more gentle, soft, and melancholy character. (Hence the name 
of Gemitores applied to this section, while the Gallinacei are 
called the Clamatores.) Besides the true Pigeons and Doves, 
this sub-order includes also the remarkable extinct bird, the 
Dodo, which was of gigantic size, comparatively speaking, and 
inhabited the island of Mauritius up to the commencement of 
the seventeenth century. 

Order V. Scansores (Lat. scando , I climb).—The order 
of Scansores or Climbing Birds is very shortly and easily de¬ 
fined, having no other distinctive and exclusive peculiarity 
except the fact that the feet have four toes, of which two are 
turned backward and two forward (Fig. 135). Of the two 
toes which are turned backward, one is the proper hind-toe, 
and the other is the outermost toe. This arrangement of 
the toes enables the Scansorial birds to climb with great 
ease and readiness. Their powers of flight are usually very 
moderate, and below the general average, and their food con¬ 
sists of insects and fruits of various kinds. Their nests are 
usually made in the hollows of old trees, but some (Cuckoos) 
have the remarkable habit of depositing their eggs in the 
nests of other birds. They are never polygamous, and the 
young are born in a naked and helpless condition. 

The following families have been established in the Scan- 
sores : 1. The Cucnlidee or Cuckoo family, comprising the true 
Cuckoos and some allied birds. They are remarkable for the 
fact that many of them are “ parasitic,” that is to say, they 
lay their eggs in the nests of other birds. The Yellow-billed 
Cuckoo ( C '. Americanus ), however, of the United States, 
builds a nest for itself and brings up its own young. 2. The 
Picidoe or Woodpecker family, comprising many familiar 
birds, all of which climb and run up trees with the greatest 
facility. They live mostly on insects, which they catch by 
darting out their long, worm-like, barbed tongue. 3. The 
Psittacidce or Parrot family, comprising the true Parrots, the 


274 


VERTEBRATE ANIMALS. 


Cockatoos, the Lories, the Parrakeets, and the Macaws. They 
are all natives of hot climates, and are most remarkable for 
their brilliant plumage, and loud, harsh, and grating voices. 



Fig. 135.—Scansores. Purple-capped Lory (Lorius domicella ). 


The beak (Fig. 135) is hooked, and is used as a kind of third 
foot in climbing, but some move about actively on the ground. 
4. The Phamphastidce or Toucans, distinguished by their 
enormously large and cellular bills, the sides of which are ser¬ 
rated. They live in deep forests, in small flocks, and are con¬ 
fined to tropical America. 5. The Trogonidce or Trogons, 
which inhabit the most retired recesses of the forests of the 
intertropical regions of both hemispheres, and are distin¬ 
guished by their resplendent plumage. 

Order VI. Insessores (Lat. insedeo , I sit upon, or perch). 
—The sixth order of Birds is that of the Insessores or Perchers , 
often spoken of as the Passerine Birds (Lat. passer , a sparrow). 


DIVISIONS OF BIRDS. 


275 



They are defined by Owen as follows: “ Legs slender, short, 
with three toes before and one behind, the two external toes 
united by a very short membrane” (Fig. 136, A, B). 

“ The Perchers form by far the most numerous order of 
birds, but are the least easily recognizable by distinctive char¬ 
acters common to the whole group. Their feet, being more 
especially adapted to the delicate labors of nidification ” 
(building the nest), “ have neither the webbed stiucture of 
those of the Swimmers , nor the robust strength and destruc¬ 
tive talons which characterize the feet of the Birds of Rapine, 
nor yet the extended toes which enable the Wader to walk 
safely over marshy soils and tread lightly on the floating leaves 
of aquatic plants ; but the toes are slender, flexible, and moder¬ 
ately elongated, with long, pointed, and slightly-curved claws. 


Fig 136 —Insessores. A. Foot of Yellow Wagtail; B, Foot of Water Ouzel; C, Conirostral 
beak (Hawfinch); D, Dentirostral beak (Shrike); E, Tenuirostral beak (Humming-bird): 
F, Fissirostral beak (Swift). 

“The Perchers, in general, have the females smaller and 
less brilliant in their plumage than the males; they always 
live in pairs, build in trees, and display the greatest art in the 
construction of their nests. The young are excluded in a blind 
and naked state, and are wholly dependent for subsistence 








276 


VERTEBRATE ANIMALS. 


during a certain period on parental care. The brain arrives 
in this order at its greatest proportionate size; the organ of 
voice here attains its utmost complexity; and all the charac¬ 
teristics of the bird, as power of flight, melody of voice, and 
beauty of plumage, are enjoyed in the highest perfection by 
one or other of the groups of this extensive and varied order.” 

The structure, then, of the feet gives the definition of the 
order, but the minor subdivisions are founded on the nature 
of the beak ; this organ varying in form according to the na¬ 
ture of the food, which may be “ small or young birds, carrion, 
insects, fruit, seeds, vegetable juices, or of a mixed kind.” In 
accordance with this character, the Insessores have been di¬ 
vided into four great sections, as follows: 

1. Conirostres —in which the bill is strong and on the 
whole conical, broad at the base and tapering with consider¬ 
able rapidity to the point (Fig. 136, C). The upper mandible 
is not markedly toothed at its lower margin. Good exam¬ 
ples of the Conirostral beak are to be found in the common 
Sparrow, Bullfinch, Crow, or Hawfinch (C). The greater part 
of the Conirostres are omnivorous, eating any thing which 
may come in their way; but some are granivorous, subsisting 
upon grains and seeds. . To this section belong the Hornbills 
(Duceridce), the Starlings ( Sturnidce ), the Crows, Jays, and 
Magpies ( Corvidce ), the Cross-bills (. Loxiadce ), and the nu¬ 
merous Finches, Buntings, Grosbeaks, Tanagers, and Larks 
{Fnngillid(je). 

2. Dentirostres .—The birds of this section are characterized 
by the fact that the upper mandible of the beak is notched or 
toothed on its lower margin near the tip (Fig. 136, D). They 
all feed upon animal food, especially upon insects. In this 
section are the Shrikes (. Laniidce ), the Fly-catchers (. Muscica - 
pidce ), the Thrushes (. Merulidce ), the Tits (Daridee), and the 
Warblers ( Sylviadce ). 

3. Tenuirostres .—In this section the beak is long and 
slender, gradually tapering to a point (Fig. 136, E). The toes 
are generally very long and slender, especially the hinder toe. 
Many live to a great extent upon vegetable juices, and among 
these are some of the most fragile and brightly-colored of all 
the birds. A great many, however, live upon insects, either 
partially or entirety, and some of these approach nearly to the 
Dentirostres in many of their characters. Among the more 
important groups included in this section are the Creepers and 
Wrens ( Certhidce), the Honey-eaters ( Meliphagidoe ), the Hum¬ 
ming-birds ( Trochilidoe ), and the Hoopoes ( TJpupince ). 


. DIVISIONS OF BIRDS. 


277 


4. Fissirostres .—The beak in the Fissirostral birds (Fig\ 
136, F) is generally short, and remarkably wide in its gape, 
and the opening of the bill is protected by a number of 
bristles. This arrangement is in accordance with the habits 
of the Fissirostres , the typical forms of which live upon in¬ 
sects and take their prey upon the wing. The most typical 
Fissirostres , in fact, such as the Swallows and Goat-suckers, 
fly about with their mouths open, and the insects which they 
catch in this way are prevented from escaping, partly by the 
bristles which border the gape, and partly by a sticky secretion 
within the mouth. The most typical Fissirostral birds are the 
Swallows and Martens (. Hirundinidce :), the Goat-suckers ( Car 
primulgidce ), and the Swifts ( Cypselidee ); but to these the 
Bee-eaters (Meropidoe) and the King-fishers (. Alcedinidce) are 
usually added. 

Order VII. Raptores (Lat. rapto, I plunder).—The 
Birds of Prey are characterized by the form of the beak, 
which is adapted for tearing animal food (Fig. 137, B). The 
upper mandible is the longest, hooked at its point, “ strong, 
curved, sharp-edged, and sharp-pointed, often armed with a 
lateral tooth” (Owen). The body is extremely muscular; the 



Fig. 137.—Raptores. A, Foot of Peregrine Falcon; B, Head of Buzzard. 


legs are robust, short, with three toes in front and one behind; 
all the toes armed with strong, curved, crooked claws or talons 
(Fig. 137, A). They all feed upon the flesh of other animals, 
which they either kill for themselves or find dead, and their 
flight is generally extremely rapid and powerful. They are 
not polygamous, and the female is larger than the male. They 
usually build their nest in lofty and inaccessible situations, and 
seldom lay more than four eggs. The young are hatched in 
a naked and helpless condition. 

13 


278 


VERTEBRATE ANIMALS. 


The Raptores are divided into two sections—the Nocturnal 
Birds of Prey, which hunt at night, and the Diurnal Birds of 
Prey, which hunt by day. In the former section is only the 
single family of the Owls (Slrigidce), in which the eyes are 
large, and are directed forward; while the plumage is exceed¬ 
ingly soft and loose, so as to render their Right almost noise¬ 
less. The Owls (Fig. 138) hunt their prey in the twilight or 
on moonlight nights, and they live mostly upon field-mice and 
small birds, but they will also eat insects and frogs. In the 



Fig. 138.—A, Foot of Tawny Owl; B, Head of White Owl. 


section of the diurnal Raptores are the Falcons and Hawks, 
the Eagles and the Vultures. In all these the eyes are smaller 
than in the Owls, and are placed laterally, and the plumage is 
not soft. They usually possess extraordinary powers of flight. 
The wings are long and pointed, the sternal keel is greatly 
developed, the pectoral muscles are of large size, and many of 
them exhibit powers of locomotion more rapid than those en¬ 
joyed by any other members of the animal kingdom. 

Of the diurnal Raptores, America has many examples, and 
some of these are among the most celebrated members of the 
entire order. Besides many Hawks, Buzzards, and Kites, may 
be especially mentioned the Bald Eagle, the Californian Vul¬ 
ture, and the Condor. The Bald or White-headed Eagle 
(Halietus leucocephalus ) is well known as the national emblem 
of the United States. It is a fine and courageous bird, and 
lives to a great extent upon fish, which it either catches for 
itself, or, more commonly, wrests forcibly from the American 
Osprey. The Californian Vulture (Cathartes Californianus) 
is the largest of the Birds of Prey, with the single exception 


DIVISIONS OF BIRDS. 


279 


of the Condor. It is entirely confined to the Pacific coast. The 
Condor ( Sarcorhampus gryphus) has a stretch of wing of 
from 12 to 14 feet, and is usually seen soaring in majestic cir¬ 
cles at great elevations, rising, it is said, to a height of over 
20,000 feet. It inhabits the lofty mountain-ranges of the 
Andes, and lays its eggs at a height of from 10,000 to 15,000 
feet. 

Order VIII. Saurur.e (Gr. saura, lizard; oura, tail).— 
This order includes only the single extinct bird, the Archaeop¬ 
teryx, which has been found in the Oolitic rocks of Germany. 
The Archaeopteryx was about as big as a common Rook, and 
shows many singular points of resemblance to the true Rep¬ 
tiles. It differs from all living birds in having two free claws 
to the wing, and in possessing a long, lizard-like tail. Instead 
of the ploughshare-shaped bone which terminates the tail in 



Fig. 139.—Archaeopteryx. Tail and detached hones. 


living birds (Fig. 129, B), the tail in the Archwopteryx is very 
longhand consists of about twenty distinct and separate ver¬ 
tebra?, each of which supports a pair of quill-feathers. The 
tail, therefore, except for the presence of feathers, must have 
been very like that of a Lizard. 




MAMMALIA. 


CHAPTER XXXI. 

CLASS V.— MAMMALIA. 

The Mammalia include all the ordinary quadrupeds, and 
may be shortly defined as comprising Vertebrate Animals in 
which some part or other of the shin is always provided with 
hairs , and the young are nourished for a longer or shorter 
time by means of a special fluid—the milk—secreted by special 
glands—the mammary glands. These two peculiarities are 
of themselves sufficient to separate the Mammals from all 
other classes of the Vertebrate sub-kingdom. In addition, 
however, to these two leading characteristics, the following 
points are of scarcely less importance: 

1. The skull is united with the spinal column by means of 
two articulating surfaces or condyles, instead of one, as in the 
Reptiles and Birds. 

2. The lower jaw consists of two halves, each composed 
of a single piece, and united in front. The lower jaw, also, is 
always jointed directly with the skull, and there is no quad¬ 
rate bone. 

3. The heart consists—as in Birds—of four distinct cham¬ 
bers, two auricles and two ventricles. The right and left sides 
of the heart are completely separated from one another, and 
there is never any direct communication between the blood 
sent to the lungs and that sent to the body. The red corpuscles 
of the blood (Fig. 99, a) are, in the great majority of cases, 
in the form of circular disks, and they never contain any inter¬ 
nal solid particle or nucleus. 

4. The cavities of the chest (thorax) and abdomen are 
separated from one another by a muscular partition, which is 
called the midriff or diaphragm, and is the chief agent in res¬ 
piration. 


MAMMALIA. 


281 


5. The respiratory organs are in the form of two lungs, 
placed in the chest, and never communicating with air-recep¬ 
tacles situated in different parts of the body. In no case and 
at no period of life are gills or branchiae present. 

As regards the skeleton of the Mammalia it is not neces¬ 
sary to add much to what was said in speaking of the Verte- 
brata generally. With few exceptions, the spinal column is 
divisible into the same regions as in man—namely, the neck 
or cervical region, the back or dorsal region, the loins or lum¬ 
bar region, the sacral region, and the tail or caudal region {see 
Fig. 95). In spite of the great differences observable in the 
length of the neck in different Mammals, the number of ver¬ 
tebrae which form the cervical region is extraordinarily con¬ 
stant, being almost invariably seven. In this respect the 
Giraffe, which is the longest-necked of Mammals, agrees with 
the Whale, which can hardly be said to have a neck at all. 
The vertebrae of the back or dorsal region are mostly thirteen 
in number, but are often more. In man there are only twelve; 
and in some cases there are only eleven or ten. The lumbar 
vertebrae are usually six or seven in number; five in man; 
rarely less than four. The sacral vertebrae are usually amalga¬ 
mated to form a single bone—the sacrum —but this is wanting 
in the Whales. The number of vertebrae in the tail or caudal 
region varies from four to as many as five-and-forty, and they 
are usually freely movable upon one another. The thoracic 
cavity or chest in Mammals is always enclosed by a series of 
ribs; the number of which varies with the number of the dor¬ 
sal vertebrae. As a rule, the ribs are united to the breastbone 
or sternum in front, not by bony pieces, as in birds, but by 
cartilages. Only the front ribs reach the sternum, and these 
are called the “ true ” ribs; the hinder ribs fall short of the 
breastbone, and are called the “ false ” ribs. The sternum is 
composed of several pieces, placed one behind the other, but 
usually amalgamated to form a single bone. It is usually long 
and narrow in shape, and is only rarely furnished with any 
ridge or keel, as it is in birds. The regular number of limbs 
in the Mammals is four, two anterior and two posterior; and 
for this reason the Mammals are often spoken of as Quadru¬ 
peds. Some Mammals, however, such as the Whales and 
Dolphins, have only the anterior limbs, and many of the Am¬ 
phibia and Reptiles walk upon four legs. As regards the 
structure of the fore-limbs (Fig. 96), the general plan of con¬ 
formation is the same as described in treating of the Verte- 


282 


VERTEBRATE ANIMALS. 


brata generally (p. 202). The shoulder-blade or scapula is 
never absent; and the coracoid bone, which is so marked a 
feature in the Birds, is with hardly an exception amalgamated 
with the scapula. The clavicles or collar-bones are often want¬ 
ing or rudimentary, but in no Mammal are they ever united 
together in front so as to form a merry-thought or “ furculum.” 
The regular number of fingers is five, but thej 7 vary from one 
to five, the middle finger being the longest and most persist¬ 
ent of all, and being the only finger left in the Horse. Prop¬ 
erly each finger consists of three short bones or phalanges, 
except the thumb, which has two; but this rule is occasionally 
departed from. While the fore-limbs are never wanting, the 
hind-limbs are sometimes absent, as in the Whales. Generally 
speaking, however, the posterior limbs are present, and the 
pelvic arch has much the same structure as in man. The foot 
—like the hand—consists regularly of five digits, but it is sub¬ 
ject to the same abortion of parts, as we shall see hereafter. 

The great majority of Mammals possess teeth, but these 
are only present in the embryo of the whalebone Whales, and 
are altogether w'anting in the scaly and great Ant-eaters. The 
teeth are also almost invariably implanted in distinct sockets 
in the jaw. Some Mammals have only a single set of teeth ; 
but in most cases the young Mammal possesses a set of what 
are called the milk-teeth, or deciduous teeth, which is ultimate¬ 
ly replaced by a second set, constituting the permanent teeth. 
No Mammal has ever more than two sets of teeth. In man, 
and in many other Mammals, the teeth are divisible into four 
groups, w T hich differ from one another in position, appearance, 
and function. These are termed respectively the incisors, ca¬ 
nines, prazmolars, and molars. It is impossible to describe 
fully which teeth come under each of these heads without en¬ 
tering into unnecessary details as to the structure of the jaws. 
It must be sufficient here to point out the general characters 
and position of these groups in a good illustrative example, 
such as one of the higher Apes (Fig. 140). The incisors (i) 
vary greatly in size and number, but they are always placed 
in the front of the mouth, and are the teeth which are used in 
simply biting or dividing the food. The canine or eye-tooth 
(c) is generally larger or more pointed than the other teeth. 
The canines are sometimes wanting, or are sometimes present 
in one jaw and not in the other; but there are never more 
than four altogether—that is to say, one in each jaw on each 
side. The praemolars and molars (pm and m) are the so-called 
“ back-teeth,” and they vary a good deal in number and function, 


MAMMALIA. 


283 


being sometimes adapted for cutting the food, but more usual¬ 
ly for chewing and grinding it down. 



All these kinds of teeth are not necessarily present, and 
the teeth constitute most important characters for separating 
the various orders of Mammals from one another. For this 
reason it is usual to express the number of the teeth in any 
particular animal by an arithmetical formula, called the dental 
formula. For example, the formula for the portion of the 
jaw of the Chimpanzee figured above (Fig. 140) would be as 
follows: 

i 2; cl; pm 2; m3. 

But this is only one half of the lower jaw, and the dental for¬ 
mula must include both sides, so that it would be: 

i 2— 2 ; c 1 —1; pm 2 — 2 ; m 3—3. 

That this would be the formula is at once evident, when it is 
remembered that the two sides of the jaw of course contain 
exactly the same teeth. Still, the formula as given above only 
includes the lower jaw, and to render it perfect it must take 
in the teeth of the upper jaw as well. This is effected by 
placing the figures in two rows separated by short lines, all 
the figures in the upper row referring to the upper jaw, and 
those in the lower row to the lower jaw; the short dashes be¬ 
tween the figures of each row still indicating the teeth on the 
two sides of the mouth. The complete formula would there¬ 
fore run as follows: 


284 


VERTEBRATE ANIMALS. 


.2—2 
1 2—2 ’ 


1—1 2—2 3—3 o . 

c -— T ; pm ^^ ; m -—« — 32. 


1—1 


2—2 ’ 3—3 


In this way the dentition —that is to say, the number and ar¬ 
rangement of the teeth—can be presented in a manner which 
can be instantly recognized by the eye. It must be remem¬ 
bered, however, that the formula seldom exhibits the regular¬ 
ity of the one of the Chimpanzee given above. The teeth 
are not necessarily the same in both jaws, and in many cases 
some may be altogether wanting. To show this there is sub¬ 
joined the dental formula of a typical Ruminant animal, such 
as a sheep: 


0—0 
3=3 ; C 


0—0 3—3 3—3 00 

; pm „ ; m -—- = 32. 


1—1 


3—3 ’ 3—3 


From this formula it will be seen that the sheep has 32 teeth 
in both jaws taken together. The upper incisors and canines 
are wanting, and there are three prasmolars and three molars 
on each side of the upper jaw. In the lower jaw there are 
six incisors, two canines, and the same number of prasmolars 
and molars as in the upper jaw. 

As regards the digestive system of Mammals, the alimen¬ 
tary canal and digestive glands have on the whole the same 
general structure and arrangement as in man (pp. 203, 204). 
Some very remarkable modifications, however, in the structure 
of the stomach and in the termination of the intestine occur 
in certain Mammals; but these will be noticed in speaking of 
the orders in which they occur. 

The cavity of the abdomen in Mammals is always separated 
from that of the thorax by a complete muscular partition—the 
diaphragm. The abdomen contains the greater part of the 
alimentary canal, the liver, pancreas, kidneys, and other or¬ 
gans. The thorax contains chiefly the heart and lungs. The 
heart is contained in a membranous sac—the pericardium, and 
consists of two auricles and two ventricles. The heart con¬ 
sists functionally of two sides, each having an auricle and a 
ventricle, which communicate with one another by apertures, 
so guarded by valves that the blood can pass from the auricle 
into the ventricle, but not, under ordinary circumstances, from 
the ventricle to the auricle. There is in the adult no direct 
communication between the two sides of the heart. The 
course of the circulation is indicated in the subjoined diagram, 
and is shortly as follows: The venous blood, which has become 
impure by passing through the tissues, is returned by the 
great veins to the right auricle, from which it passes into the 


MAMMALIA. 


285 


right ventricle. From here it is driven through a great vessel, 
called the pulmonary artery, to the lungs, where it is submitted 
to the action of the air, and becomes arterial blood. It is then 
returned to the heart by a series of vessels, called the pulmo¬ 
nary veins, and is poured into the left auricle, from which it 
passes into the left ventricle. From 
the left ventricle it is propelled to 
all parts of the body by a great 
systemic vessel, which is called the 
aorta (Fig. 141). 

The lungs of Mammals are two 
in number, and differ from those of 
Birds in being freely suspended in 
membranous bags. They are spongy 
and cellular throughout, and they 
never communicate by apertures on 
their surface with air-sacs placed in 
different parts of the body. 

The nervous system of Mammals 
is chiefly remarkable for the great 
proportionate development of the 
brain, as compared with the spinal 
cord. 

In the higher Mammals, also, 
the two halves (hemispheres) of the 
brain proper {cerebrum) are con¬ 
nected together by a great band or 
bridge of nervous tissue, constitut¬ 
ing w T hat is known as the corpus 
callosum. This structure is not a 
conspicuous feature in the two low¬ 
est orders of the Mammalia. The 
senses, as a rule, attain great per¬ 
fection in the Mammals; and the 
only sense which can ever be said to be entirely wanting is 
that of sight. Eyes, however, are always present, though 
they may be rudimentary; and in those Mammals which are 
said to be “ blind,” it is not generally that the eyes are want¬ 
ing, but that the skin passes unbrokenly over the eyeball, or 
the optic nerve is degenerated. Even in these cases, how T ever, 
it is not impossible that there maybe some perception of light 
through the skin. An external ear for collecting sounds is 
usually present; but it is wanting in the Whales and Dol¬ 
phins, and in some of the Seals. 



Fig. 141. —Diagram of the circulation 
in a Mammal. (The cavities con¬ 
taining venous blood are marked 
black, those containing arterial 
blood are left white.) a Eight 
auricle; v Eight ventricle; p Pul¬ 
monary artery carrying venous 
blood to the lungs; pv Pulmonary 
veins carrying arterial blood from 
the lungs; a' Left auricle; Left 
ventricle; b Aorta carrying arte¬ 
rial blood to the body; cVena cava 
carrying venous blood to the heart 



286 


VERTEBRATE ANIMALS. 


The shin is invariably furnished over a greater or less part 
of its surface with the epidermic appendages known as hairs, 
which differ from feathers chiefly in not splitting up as they 
are produced. In the scaly Ant-eater (Manis), the hairs are 
aggregated together so as to form horny scales; and in the 
Hedge-hog, Porcupine, and other animals, many of the hairs 
are developed into long spines or prickles. In other cases, 
again, as in the Armadillos, the skin is more or less covered 
by an armor of bony plates. The only apparent exception to 
the universal presence of hair on some part or other of the in¬ 
tegument of all Mammals is constituted by the true Cetaceans 
(Whales and Dolphins), many of which are without hair when 
grown up. Some, however, such as the Whales, have a few 
bristles in the neighborhood of the mouth, even when adult. 
And the Dolphins, which are totally hairless when grown 
up, exhibit tufts of hair upon the muzzle before they are 
born. 

The young Mammal is always born in a helpless condition, 
and is nourished for a longer or shorter time by means of the 
milk of the mother. The milk is secreted by special organs, 
called the mammary glands, which are present in both sexes, 
but are normally undeveloped in the male. The number and 
position of the mammae vary a good deal in different cases, 
but they are always placed on the lower surface of the body, 
and their ducts almost always open upon a special eminence, 
called the teat or nipple. In one or two cases, however, the 
mammary glands open by simple slits in the skin of the abdo¬ 
men, and not by distinct nipples. In ordinary Mammals the 
milk is obtained by voluntary suction on the part of the young, 
but in the Marsupials (Kangaroos, Opossums, etc.) the milk is 
forced into the mouth of the young animal by the action of a 
special muscle. 

So much difference of opinion obtains as to the best foun¬ 
dation upon which to establish a division of the Mammalia 
into great primary sections, that it has been thought advisable 
to leave this subject wholly out of consideration. For our 
present purpose it is enough to adopt the old classification of 
Mammals into the two great divisions of the Placental and 
Non-placental forms. In the Placental Mammals the young 
is nourished within the body of the mother by means of a 
structure called the placenta, or “ after-birth,” through which 
the nutrient materials of the mother’s blood reach the young. 
In consequence of this, the young of the Placental Mammals 
can be retained within the body for a considerable period, and, 


MAMMALIA. 


287 


when born, they are able to obtain their natural food—the 
milk—by their own exertions. In the Non-placental Mam¬ 
mals, on the other hand, the young are born at an extremely 
early period of their development, before there is any necessity 
that a placenta should be formed for the nourishment of the 
foetus. In these cases, therefore, the young when born are 
much more immature and helpless than in the case of the 
Placental Mammals. So helpless are they, that they are even 
unable to suck, and have in most cases to be fixed by the 
mother herself upon the teats, while the milk is forced into 
their mouths by a muscle which is spread over the mammary 
gland. Adopting these primary sections as practically suf¬ 
ficient in an elementary work, the whole class of the 
Mammalia may be divided into the following fourteen 
orders: 


Division A.—Aplacental Mammals. 
Order 1.— Monotremata. 

Order 2.— Marsupialia. 

Division B.—Placental Mammals. 
Order 3.— Edentata. 

Order 4.— Sirenia. 

Order 5.— Cetacea. 

Order 6.— Uugulata. 

Order 7.— Hyracoidea. 

Order 8.— Proboscidea. 

Order 9.— Carnivora. 

Order 10.— Rodentia. 

Order 11.— Cheiroptera. 

Order 12.— Insectivora. 

Order 13.— Quadrumana. 

Order 14.— Bimana. 


CHAPTER XXXII. 


__ ) 

ORDERS OF MAMMALIA. 

Order X. Monotremata (Gr. monos , single ; trema , aper¬ 
ture).—The first and lowest order of the Mammals—that of 
the Monotremata —comprises only two very remarkable ani¬ 
mals, both of which are exclusively confined to New Holland. 
These are the Duck-mole ( Ornithorhynclius) and the Porcupine 
Ant-eater (Echidna). The Monotremata are essentially charac¬ 
terized by the fact that, as in Birds, the termination of the in¬ 
testine opens into a common chamber or cloaca , which receives 
also the ducts of the urinary and reproductive organs. The 
jaws are destitute of true teeth; but the Ornithorhynclius 
has a kind of beak, like the bill of a duck, furnished with 
small horny plates, which act as teeth. The pectoral arch, 
which supports the fore-limbs, resembles that of Birds in 
several respects, but especially in the fact that the coracoid 
bones are distinct, and are not amalgamated with the shoulder- 
blade. There is no pouch developed on the abdomen of the 
females, but there are the so-called “ marsupial bones.” These 
are two small bones which arise from the front of the pelvis. 
They are really to be regarded as formed by a conversion into 
bone of the tendons of one of the muscles of the abdomen. 
There are no external ears. The mammary glands have no 
nipples, and the young are said to be devoid of a placenta. . 

The Duck-mole (Fig. 142) is one of the most extraordinary 
of Mammals, and is found inhabiting the rivers and lakes of 
Australia and Tasmania. The body resembles that of a small 
otter, and is covered with a short brown fur. The tail is 
broad and flattened, and the jaws are sheathed with horn, so 
as to form a flattened beak, very like the bill of a duck. The 
legs are short, furnished with five toes each, and webbed, so 
that the animal swims with great facility. Their food consists 



ORDERS OF MAMMALIA. 


2S9 


chiefly of aquatic insects and mollusks, and they make very 
extensive burrows in the banks of streams. 



Fig. 142. —Monotremata. Duck-mole (Ornithorhynchus paradoosus). 
(After Waterhouse.) 


The other member of the Monotremata is the Porcupine 
Ant-eater or Eihidna , which is not unlike a large hedgehog 
in appearance. The snout is very long, and is enclosed in a 
continuous skin till close upon its extremity, where there is a 
small aperture for the protrusion of a long and flexible tongue. 
There are no teeth, nor any organs to act as teeth. The feet 
have five toes each, and are furnished with strong digging- 
claws, but the toes are not webbed. The skin is covered with 
strong prickly spines interspersed with bristly hair. The 
Eehidna measures from fifteen to eighteen inches in length, 
and is a nocturnal animal. It lives in burrows, and feeds 
upon insects, which it captures by protruding its long, sticky 
tongue. 

Order II. Marsupialia.— The name of Marsupials is de¬ 
rived from the fact that the females of this order are mostly 
furnished with an abdominal pouch or marsupium, within 
which the nipples are situated. When born, the 3 r oung are 
placed by the mother within this pouch, where they adhere to 
the teats, and can be carried about without injury. Even 
when further advanced in their development, the younsr often 
betake themselves to the shelter of the marsupium. The so- 
called “marsupial bones” are present, and as they spring 
from the front of the pelvis they no doubt serve to sunport the 
pouch ; but this cannot be their sole use, as they exist in the 
males, and also in the Monotremes, in whom there is no pouch. 
All Marsupials possess teeth, and the pectoral arch has now 
the same form as in the higher Mammals, the coracoid bones 


290 


VERTEBRATE ANIMALS. 



being now amalgamated with the shoulder-blade. The intes¬ 
tine does not terminate in a cloaca. 

Though the Marsupialia form an extremely natural order, 
sharply separated from the other Mammals, they include a 
large number of varied forms. In fact, this order, from its 
being the almost exclusive possessor of a continent so large as 
Australia, has to discharge, in the general economy of nature, 
functions which are elsewhere performed by several orders. 
As regards their geographical distribution, with the single 


Fig. 143.—Marsupialia. The Koala or Kangaroo-bear (Phascolarctos cmereun). 
(After Gould.) 


exception of the family Didelpliidce (the true Opossums), the 
whole order of the Marsupials is exclusively confined to Aus¬ 
tralia, Van Diemen’s Land, New Guinea, and the adjacent 
islands. 

The Marsupials may be primarily divided into the vege¬ 
table-eating and rapacious or carnivorous forms—the former 
characterized bv the absence or rudimentary condition of the 
canine teeth, the molars having broad, grinding crowns; 
while in the latter there are well-developed canines, and the 
molars are not adapted for grinding*. Of the vegetable-eating 
forms, the best known are the Kangaroos ( Macropodidce ), 
distinguished by the remarkable disproportion between the 


ORDERS OF MAMMALIA. 


291 


hind and fore limbs, the former being bj far the longest and 
strongest. By their long hind-legs, assisted by a powerful 
tail, the Kangaroos can perform astonishing jumps, and, in 
fact, leaping is their mode of progression w T hen pursued. 

The typical Kangaroos live on the great grassy plains of 
Australia; but the Tree Kangaroos spend a great part of 
their time in trees, and the Rock Kangaroos affect mountainous 
districts. The Kangaroo-bear or Native Sloth (. Phascolarc ■» 
tos cinereus , Fig. 143) has no tail, and has the body covered 
with a short, dense fur, while the ears are tufted. The fore¬ 
feet can be used as hands, and the toes are all furnished with 
strong, curved claws. It is a harmless, nocturnal animal, and 
spends most of its existence in trees. The typical group, 
however, of the vegetable-eating Marsupials is that of the 
Fhalangers, comprising a large number of small animals which 
live in trees, and generally possess a prehensile tail. The 
most familiar example is the Australian “Opossum” ( Phalan - 
gista vulpina ), which is largely hunted by the natives. In 
the so-called “flying” Phalangers, again, the tail is not pre¬ 
hensile, and the animal takes extensive leaps from tree to 
tree, by means of a fold of skin which stretches between the 
body and the fore and hind limbs. 

Of the carnivorous Marsupials, the Bandicoots (j PeramelesY 
the Native Devil (. Dasyurus ), the Native Tiger {Thylacinus ), 
and the American Opossums (Didelphidcz) , may be mentioned. 
The Bandicoots are little, rabbit-like Australian animals, which 
live upon insects, and seem to fill the place held in the Old 
"World by the Hedgehogs and Shrew-mice. The Native Devil 
and Thylacine, though both of comparatively small size, are 
extremely ferocious, and do much mischief to the flocks of the 
Tasmanian colonists. About twenty species of Didelphidcv 
are known, and they are all exclusively confined to the Ameri¬ 
can Continent. They are all of small size, have prehensile 
tails, and mostly live among trees. The best-known species 
is the Virginian Opossum ( Didelphys Virginiana). 

Order III. Edentata (Lat. e, without; dens , tooth).— 
This order of Placental Mammals comprises the Ant-eaters, 
Armadillos, and Sloths, and is characterized by the fact that 
the teeth are not covered with enamel, have no complete 
roots, and are never replaced by a second set. Further, in 
none of the Edentates are there any central incisor teeth, and 
in all but one there are no incisors at all. In two genera only 
are there no teeth; so that the name Edentata is not a very 


292 


VERTEBRATE ANIMALS. 


appropriate one. In all, the toes are furnished with long and 
powerful claws. 

The Edentata admit of division into two sections, accord¬ 
ing as they live upon a vegetable diet and live in trees, or are 
carnivorous and live upon or below the ground. In the first 
section are only the Sloths ( Bradypodidce ), which are exclu¬ 
sively confined to South America, inhabiting the vast primeval 
forests of this continent. They are in every way adapted for 
an arboreal life, and are 44 destined to be produced, to live, and 
to die on trees.” They are excessively awkward when upon 
the ground; but the feet are furnished with extremely long, 
curved claws, so that the animal is enabled to move about 
freely, suspended back downward from the branches of the 



Fig. 144.—Edentata. {Chlarnyphorus trmicatm.) 


trees. The Armadillos ( Dasypodidce ) are also exclusively 
confined to South America; but they are carnivorous, burrow¬ 
ing animals, and are furnished with strong digging-claws. 
The upper surface of the body is covered with a kind of armor, 
formed of hard, bony plates or shields, which are united at 
their edges (Fig. 144). Most of them can roll themselves up 
into a ball, and they can all bury themselves in the ground 
when pursued. 

The remaining South American Edentates are the hairy 
Ant-eaters, of which the best known is the great Ant-eater 
(Myrmecophaga jubata). The body in this family is covered 
with hair, the tail is long, and the teeth are altogether want¬ 
ing. They feed chiefly upon ants and termites, which they 



ORDERS OF MAMMALIA. 


293 


catch by protruding their long and sticky tongues, having 
previously broken into the nests by means of their strong, 
curved claws. 

The Edentata are represented in the Old World by only 
two genera. One of these is the genus Manis , comprising 
the scaly Ant-eaters or Pangolins, which are exclusively con¬ 
fined to Asia and Africa. In these singular animals the body 
and tail are covered by a flexible armor, composed of horny 
plates or scales overlapping like the tiles of a roof. The 
other genus is Orycteropns , comprising only the so-called 
Ground-hog of South Africa; which also lives upon insects, 
and burrows by means of its strong digging-claws. 

As regards the geographical distribution of the Edentata , 
it is to be remembered that the order has a very limited range 
at the present day. The true Ant-eaters, the Armadillos, 
and the Sloths, are exclusively confined to South America, in 
which country a group of gigantic extinct Edentates existed 
in the later portion of the Tertiary epoch. The scaly Ant- 
eater is common to Asia and Africa; and the Ground-hog is 
confined to South Africa. 

Order IV. Sirenia (Gr. seiren , a Mermaid).—This order 
comprises only certain large marine Mammals, known as Du- 
gongs and Manatees, which w~ere long classed with the Whales 
and Dolphins [Cetacea). They agree with the Whales in the 
adaptation of the body to an aquatic life, especially in the 
facts that the anterior limbs are converted into swimming- 
paddles, the hind-limbs are wholly wanting, and the hinder 
end of the body forms a powerful caudal fin, which is placed 
so as to strike the water horizontally, and not vertically as in 
Fishes. They differ from the Cetacea in having the nostrils 
placed at the anterior part of the head, and in having molar 
teeth with fiat crowns, adapted for a vegetable diet. Fleshy 
lips are present, the upper one usually with a mustache, and 
the skin is covered with scanty bristles. The head is not dis¬ 
proportionately large as compared with the body, and there is 
a tolerably distinct neck. They are vegetable-eaters, feeding 
chiefly upon sea-weeds, and haunting the mouths of rivers and 
estuaries. 

The only existing Sirenia are the Manatee ( Manatus ) and 
the Dugong (. Halicore ), often called “ Sea-cows.” The Man¬ 
atees are found on the east coast of America, and on the w^st 
coast of Africa. They are large, awkward animals, attaining 
a length of from eight to ten or fifteen feet, and their flesh is 


294 


VERTEBRATE ANIMALS, 


said to be very palatable and wholesome. The Dugongs (Fig. 
145) differ little in appearance and habits from the Manatees. 
They are found on the coasts of . the Indian Ocean and the 
north coast of Australia, and are often killed and eaten. They 
attain a length of from eighteen to twenty feet. The bones 
of the skeleton are remarkable for their extreme hardness and 
density. 



Besides these living forms, the Sirenia were represented 
by a gigantic species which formerly inhabited Behring Island 
on the coast of Kamtchatka. This animal was described by a 
M. Steller who accompanied Behring on his second expedition, 
and he named it Rhytina. This enormous animal attained a 
length of twenty-five feet, and a circumference of twenty feet, 
and it appears to have been completely exterminated, no spe¬ 
cimen having been seen for two centuries. 

Order V. Cetacea (Gr. Icetos, a Whale).-—This order 
comprises the Whales, Dolphins, and Porpoises, and it is 
characterized by the complete adaptation of its members to a 
watery life. The body is completely fish-like in form, the fore¬ 
limbs are converted into swimming-paddles, and the hind- 
limbs are completely wanting; while the hinder end of the 
body forms an extremely powerful, horizontal caudal fin. 
Sometimes there is a dorsal fin as well. The nostrils may be 
single or double, but always are placed on the top of the head, 
constituting the “ blow-hole.” The body is very sparingly 
furnished with hairs, or is wholly without them in the adult. 
The head is generally of disproportionately large size as com¬ 
pared with the body, and is rarely separable from the trunk 
by any distinct constriction or neck. There is no sacrum, and 
the pelvis is only represented in a rudimentary form. Lastly, 
the adult is either wholly destitute of teeth, or possesses onlv 



ORDERS OF MAMMALIA. 


295 


a single set, which are always conical in shape, and are never 
divisible into distinct groups. All the true Cetacea are car¬ 
nivorous, living upon animal food. 

Chief among the Cetaceans in importance and zoological 
interest are the Whalebone Whales (j Balcenidce), in which 
the adult is destitute of teeth, though the young whale pos¬ 
sesses teeth which never cut the gum. The place of teeth is 
taken by a series of transverse plates of whalebone or baleen , 
which are used as a kind of screening apparatus or filter to 
separate from the sea-water the minute Mollusks and Jelly¬ 
fishes upon which these enormous animals live. The most 
important member of this family, from a commercial point of 
view, is the Greenland Whale (Balcena mysticetus ), which 
yields most of the whale-oil and whalebone of commerce. The 
Greenland Whale attains a length of from forty to sixty feet, 
and of this enormous length about a third is taken up by the 
head alone. The oil is derived from a thick layer of fat or 
“blubber,” which is situated under the skin, and serves to pro¬ 
tect the animal from cold. Though an inhabitant of the sea, the 
w hale is obliged to come to the surface to breathe, and in so 
doing it ejects from the blow-holes w T hat looks like a column 
of water, the whole operation being knowm to the whalers as 
“ blowing.” The true nature of this act is still somewhat 
questionable, but it appears certain that the apparent jet of 
water is in. reality, mainly if not entirely, due to the condensa¬ 
tion of the moisture which is contained in the air expelled from 
the lungs. The old view was that “ blowing ” consisted in 
the whale ejecting through the nose the water which had pre¬ 
viously been filtered through the baleen-plates of the mouth ; 
but it appears to be quite certain that this view, at any rate, 
is not the correct one. The Rorquals or Finner Whales re¬ 
semble the Greenland Whale in most respects, but the skin is 
furrow ed wdth deep plaits or folds, and there is a dorsal fin, 
placed on the back. Some of these attain a gigantic size 
(eighty feet or more), but they are seldom captured, as their 
commercial value is small. 

The Toothed Whales ( Odontoceti ) are best known by the 
Sperm Whale, an animal as large as, or larger than, the Green¬ 
land Whale, but distinguished by having numerous conical 
teeth, a single blow-hole, and a curiously-truncated head. 
They yield an excellent oil, and the singular fatty substance 
which is known as “spermaceti.” They also yield the sub¬ 
stance called “ ambergris,” which is used as a perfume; but 
this is probably a product of disease. 


296 


VERTEBRATE ANIMALS. 


The last family of the Cetacea is that of the Delphinidoe , 
comprising the Dolphins (Fig. 146) and Porpoises. They have 
numerous conical teeth in both jaws, and the nostrils open by 
a single aperture on the top of the head. The Dolphins are 



Fig. 146.—Cetacea. The Common Dolphin (Delphinus ddphis). 


inhabitants of the sea, but two species live in rivers—one in 
India, and the other in America. The Porpoises are also 
marine, and occur in all seas. The most remarkable of the 
Delphinidce is the Narwhal or Sea-Unicorn, which is found in 
the Arctic seas, and which attains a length of as much as fif¬ 
teen feet in the body alone. The chief peculiarity of the Nar¬ 
whal is in the dentition. The females, as a rule, have no teeth, 
the upper jaw alone having tw r o rudimentary incisors which 
never cui. the gum. In the males, however, while the lower 
jaw io without teeth, one of the two central incisors of the 
upper jaw is enormously developed, and grows throughout 
the life, of the animal. It forms a tusk of from eight to ten 
feet in length, the whole surface of which is spirally twisted. 
The function of this extraordinary tooth is doubtless offensive. 

Order VI. Ungulata (Lat. ungula, a hoof).—This order 
is often spoken of as that of the Hoofed Quadrupeds, and is 
one of the largest and most important of the orders of Mam¬ 
malia. The order is characterized by having all the four limbs 
and by having that portion of the toe which touches the 
ground encased in a greatly-expanded nail or hoof. There are 
never more than four full-sized toes to each leg, and owing to 
the presence of hoofs the limbs are useless for grasping, and 
are only of use in locomotion and iii supporting the w r eight of 
the body. There are always tw T o sets of teeth, and the molars 
have broad crowns adapted for grinding vegetable sub¬ 
stances. 

The TJngulata are divided into two great primary sections, 
according as the toes are even or odd in number: 




ORDERS OF MAMMALIA. 


297 


A. Perissodactyla , or Odd-toed Ungulates , 

are odd in number—either one or three* If horns 
are present , they are not in pairs. 

B. Artiodactyla , or Even-toed Ungulates , in which the 
toes are even in number—either two or four / and , (/* 
horns are present, they are in pairs. 

The living Perissodactyle Ungulates are the Rhinoceroses, 
the Tapirs, and the Horse and its allies. The Bhinoceroses 
are extremely large and bulky brutes, having a very thick and 
nearly hairless skin, usually thrown into deep folds. The 
feet (Fig. 147, D) are furnished with three toes each, all en- 



Fig. 147.—Ungulata. A, Perissodactyle foot of Zebra. B, Artiodactyle foot of Llama. 

C, Artiodactyle foot of Antelope. 1>, Perissodactyle foot of lihinoceros. 

cased in hoofs. The nose is furnished with one or two horns, 
composed of longitudinal fibres compacted together, and not 
having any central core of bone. When there is only one 
horn, it is, of course, unsymmetrical; and, when there are two, 
these are not paired, but one is always placed behind the other 
in the middle line of the head, and the hinder one is much the 
shorter. The various species of Rhinoceros are found in 
India, Java, Sumatra, and Africa, inhabiting marshy places 
and feeding chiefly on the foliage of trees. The Tapirs have 
four toes to each of the fore-legs, but only three toes on the 
hind-legs, so that they are properly odd-toed. The nose forms 
a short, movable proboscis, used in stripping off the leaves of 
trees. They are large, clumsy animals, which inhabit South 

* The fore-feet of the Tapirs are even-toed, but the hind-feet are perissodactyle. 







298 


VERTEBRATE ANIMALS, 


America, Sumatra, and Malacca. The third and last family of 
the Eerissodactylci is that of the Equidce , comprising the 
Horse, Ass, Zebra, and Quagga. In this family the toes are 
reduced to one to each foot, enclosed in a single broad hoof, 


without any supplementary hoofs. There is a continuous 
series of incisor teeth in both jaws, and in the m&les canines 
are present. The dental formula is: 


. 3—3 1—1 , , 3—3 3—3 

* 3=3 1 ' C 1=1 (° r none ) ’ P m 3=3’ m 3=3 


All the varieties of Horses appear to be descended from 
the single species Equus caballus , which seems to have been 
primitively a native of Central Asia. When the American 
Continent was discovered it certainly possessed no living horse, 
but the horse has now become completely naturalized there, 
and we know that America formerly possessed about twenty 
species of horses, all of which are now extinct. In the genus 
Asinus are the Asses, Zebras, and Quaggas. The Wild Ass 
is a native of Asia, and the domestic Ass is probably descended 
from it. The Zebras and Quaggas are exclusively African, and 
are distinguished by their beautifully-striped and banded 
bodies. 

The Artiodactyles or Even-toed ITngulates are divided into 
two groups: 

1. Omnivora, as the Pig and Hippopotamus. 

2. Euminantia , which chew the cud, such as Oxen, Deer, 
Camels, etc. 

Of the Omnivorous forms the Hippopotamus or River- 




ORDERS OF MAMMALIA. 


299 


horse is characterized by its massive heavy body, short blunt 
muzzle, and feet with four hoofed toes each. The Hippopota¬ 
mus is found in the rivers of Abyssinia, and throughout the 
whole of Africa to the south of this. It reaches a length of 
from eleven to twelve feet, is nocturnal in its habits, and swims 
and dives with great facility. It lives upon vegetable food, 
and is tolerably harmless unless attacked or irritated. The 
Pigs, Peccaries, and Wart-hogs, constitute the family Suida , 
and have usually four toes to each foot, though sometimes the 
hind-feet have only three toes. All the toes are hoofed, but it 
is only two which support the weight of the bod}^, the remain¬ 
ing toe or toes being placed at some elevation on the back of 
the foot. The snout is truncated and cylindrical, and is ca¬ 
pable of extensive movement. The tail is very short, or is 
represented only by a tubercle. 

Of the Swine the most important and best known is the 
Wild Boar ( Sus scrofa ), from which it is probable that all our 
domestic varieties of swine have sprung. Another form is the 
Babyroussa or Hog-deer (Sus babyrussa ), which inhabits the 
Ihdian Archipelago, and is remarkable for the great size and 
backward curvature of the upper canine teeth. The Wart- 
hogs (. Phacochoerus ) are African, and derive their name from 
the possession of a fleshy wart under each eye. The Peccaries 
are exclusively American, the best-known species being the 
Collared Peccary (Dicotyles torquatus). They are not at all 
unlike small pigs both in appearance and habits, and they are 
generally found in small flocks. 

The Ruminantia form a most natural group of the TJngu- 
lata , characterized by the structure of the foot, the dentition, 
and the structure of the stomach. 

The foot is “ cloven,” consisting of a symmetrical pair of 
toes, encased in hoofs, and looking as if produced by the cleav¬ 
age of a single hoof. In most cases there are also two small 
supplementary hoofed toes placed on the back of the foot. 

As regards the dentition, the typical state of things is that 
there should be no incisor nor canine teeth in the upper jaw, 
but that the lower jaw should have six incisors and two canines, 
which are all similar in size and form, and constitute a con¬ 
tinuous and uninterrupted series of eight teeth placed in the 
front of the lower jaw. There are six molar teeth on each 
side of each jaw, and these have grinding surfaces. The typi¬ 
cal dental formula, therefore, for a Ruminant is: 

. 0—0 0—0 , 6—6 QO 
* 3-3 ; C 1-1 ; pm and m 6-6 = 33 


300 


VERTEBRATE ANIMALS. 


In the absence of incisor teeth in the upper jaw, the lower 
incisors bite against a callous pad of hardened gum. The 
Camel tribe differs in its dentition from the above typical 
formula, and certain exceptions likewise occur in the males 
of some other forms, and in one or two other less important 
instances. 

The stomach in the Ruminants is complex, and is divided 
into several compartments, this being in accordance with their 
mode of eating. They all, namely, “ ruminate ” or “ chew the 
cud; ” that is to say, they first swallow their food unmasti¬ 
cated, and then bring it up again after a longer or shorter 
period in order to chew it. This is effected as follows (Fig. 
149): The gullet opens at a point between the first two com- 



Fig. 149. —Stomach of a Sheep, o Gullet; r Rumen or Paunch; h Honeycomb bag or 
Reticulum ; p Many-plies or Psalteriwm ; a Abomasum or Fourth Stomach. 


partments or stomachs, of which the largest lies to the left and 
is called the “ paunch,” while the smaller right cavity is called 
the “ honeycomb bag ” ( reticulum ). The paunch (rumen) is 
the cavity into which the food is first received, and here it is 
moistened and allowed to soak for some time. After the food 
has lain sufficiently long in the paunch, it passes into the 
“■honeycomb bag,” where it is made up into little balls or 
pellets, which are then returned to the mouth by a reversed 
action of the muscles of the gullet. After having been thor¬ 
oughly chewed, and prepared for digestion, the food is now 
swallowed a second time. On this occasion, however, instead 
of passing into the paunch, the masticated food is conveyed 
into the third stomach. This is known as the “ many-plies ” 
or “ psalterium” because its lining membrane is thrown into 
a number of longitudinal folds, like the leaves of a book. The 




ORDERS OF MAMMALIA. 


301 


psalterium opens by a wide aperture into the fourth and last 
stomach, known as the “ abomasum .” This is a cavity of 
considerable size, which secretes the true digestive fluid (gas¬ 
tric juice), and it is here that the food is really digested. The 
abomasum terminates, of course, in the commencement of the 
small intestine. 

The Huminantia include a number of families, of which it 
is only possible to notice the leading characters of the more 
important ones—namely, the Camelidce , Cervidce , Giraffes , 
and Cavicornia. 

The family Gamelidoe comprises the Camel and Dromedary 
of the Old World and the Llamas of the New, and is charac¬ 
terized by having no horns, by having two incisors in the 
upper jaw, and a pair of canines in both jaws ; while the foot 
consists of only two toes, covered with imperfect nail-like 
hoofs, and destitute of the two supplementary toes. The soles 
of the feet are covered with a callous horny integument upon 
which the animal walks. In the Camels the toes are conjoined 
below by a callous pad, and the back is furnished with one or 
two fleshy humps. The Arabian Camel or Dromedary has but 
one hump, and its structure admirably adapts it for a beast of 
burden in the sandy deserts of Arabia and Africa. One special 
provision toward this end is the possession of large cells in 
the paunch, in which a large quantity of water can be stored 
up, thus enabling the animal to travel for days without drink¬ 
ing. The Bactrian Camel resembles the Dromedary in most 
respects, but it possesses two humps. The place of the Camels 
of the Old World is filled in South America by the Llamas and 
Alpacas ( Auchenia ), which have separate toes, and have no 
hump. The Llama is extensively used as a beast of burden, 
but the Alpaca is chiefly of value for its long wool, which is 
largely manufactured. 

The family Cervidce includes the true Deer, and is charac¬ 
terized by the fact that the forehead carries two solid bony 
antlers, which are not hollow, and are usually much branched. 
With the single exception of the Reindeer, these appendages 
are exclusively confined to the males, and they are deciduous; 
that is to say, they are only produced at certain seasons (an¬ 
nually, at the breeding-season), and, when they have fulfilled 
their purpose, they are shed. They increase in size and in 
the number of branches every time they are reproduced, till in 
the old males they may attain an enormous size. Among the 
more familiar of the Deer may be mentioned the Elk, or Moose 
(Alcss Americanus) of Scandinavia and North America, the 


302 


VERTEBRATE ANIMALS. 


Reindeer and Caribou ( Cervus tarandus) of Northern Europe, 
Asia, and North America; the Red Deer ( Cervus elaphus , Fig 1 . 
150) of Europe; the Wapiti (C. Canadensis) of Canada; and 
the Roebuck ( Capreolus caprcea) of Northern Europe. 



Fig. 150.—Cervidse.—Head of Stag (Cervus elaphus). 


Of the Giraffes or Camelopardalidce there is only a single 
living species, exclusively confined to the African Continent. 
Both sexes have two pairs of short horns, carried on the fore¬ 
head ; but these are persistent, and are covered with a hairy 
skin. The neck is extremely long, and the fore-legs much 
longer than the hind-legs. It is the largest of living Ruminants, 
and measures as much as from fifteen to eighteen feet in 
height. 

The Cavicornia or Hollow-horned Ruminants comprise 
the Oxen, Sheep, Goats, and Antelopes, and are characterized 
by having horns, which may be present in one Or both sexes, 
and consist of a horny sheath surrounding a central bony axis, 
or “ horn-core.” The horns are persistent, and are not peri¬ 
odically shed, and there is usually only a single pair, though 
sometimes there are two pairs. In their dentition, and in 



ORDERS OF MAMMALIA. 


303 


other respects, the Cavicornia are to be regarded as being 
the most typical examples of the Huminantia , and they in¬ 
clude a number of animals which are of the highest utility to 
man. The Antelopes form a very extensive group, closely re¬ 
sembling the true Deer, but distinguished by the possession 
of hollow horns, in place of solid antlers. Most of the Ante¬ 
lopes are African, and there are only two European forms (the 
Chamois being one), while America possesses only the Prong- 
buck [Antilope furcifer). Among the more familiar African 
species may be mentioned the Gazelle, the Koodoo (Fig. 151), 



Fig. 151.—Antelopidae. Head of the Koodoo (Strepsiceros Koodoo). 


the Gnu, the Gemsbok, and the Springbok. The Sheep and 
the Goats [Ovidce) are closely allied to one another, and are 
well known by their domestic varieties. All the Sheep appear 
to be natives of the Old World, with the exception of the 
“ Bighorn ” (Ovis montana) of the Rocky Mountains. Among 
the "true Oxen (. Bovidce) the most important species is the 
domestic Ox (Bos taunts) with its innumerable varieties. The 
true Buffalos ( Bubalus) are natives of Asia and Africa, and 
are characterized by their wide horns united at the base. The 
American Buffalo, 'or Bison, as it is properly called [Bison 
Americanus), is distinguished by its enormous head, shaggy 
mane, and conical hump between the shoulders. America also 
nossesses another singular Ox in the person of theMusk Ux 
(Ovibos moschatus ), which is found north of the 60th parallel, 
and is remarkable for its small size and long, woolly coat. 

Order VII. Hyracoidea (Gr. hurax, a shrew \eidos, 
form).—This order includes only a single small genus (. Uyrax ), 


304 


VERTEBRATE ANIMALS. 


of which only a few species are known. They are all gregarious 
little animals, living in holes of the rocks, and capable of do¬ 
mestication. One species (Hyrax Capensis ) occurs commonly 
in South Africa, and is known to the Dutch colonists as the 
“ Badger.” Another species (Hyrax Syriacus) occurs in the 
rocky °parts of Arabia and Palestine, and is believed to be the 
“ cony ” of Scripture. They present many curious points of 
resemblance to the gigantic Rhinoceros, and are often placed 
in the same order, the similarity being especially great as re¬ 
gards the form of the molar teeth. The incisor teeth of the 
upper jaw are long and curved, with sharp cutting edges, and 
they grow from a permanent pulp, thus resembling the teeth 
of the genuine Rodents (such as the Rabbit or Beaver). 

Order VIII. Proboscidea (Lat. proboscis , the snout).— 
This order is only represented at the present day by the Ele¬ 
phant, of which there are only two species living. One of 
these is the African Elephant, which is distinguished by its 
convex forehead and great flapping ears; the other is the In¬ 
dian Elephant, which has a concave forehead and small ears. 
The Proboscidea are characterized by having the nose pro¬ 
longed into a cylindrical trunk or proboscis, at the extremity 
of which the nostrils are placed (Fig. 152, n). The trunk is 
extremely flexible and highly sensitive, and terminates in a 
finger-like prehensile lobe. There are no canine teeth; the 
molars are few in number, large, and transversely ridged, or 
furnished with tubercles. In the living forms there are no 
lower incisors, but the upper incisors are two in number, grow 
from a permanent pulp, and constitute enormous tusks (Fig. 
152, i). In some of the extinct forms there are two tusk-like 
lower incisors, and sometimes both the lower and upper in¬ 
cisors are developed into tusks. The feet are furnished with 
five toes each, but these are only partially indicated externally 
by the divisions of the hoof. The animal walks upon thick 
pads of integument, which constitute the soles of the feet. 
The Indian Elephant inhabits India and the Indian Archi¬ 
pelago and has five hoofs on the fore-feet, but only four on the 
liind-feet. Like the Ceylon Elephant, which is a mere variety, 
the males alone possess well-developed tusks. The African 
Elephant has four hoofs on the fore-feet, and only three on 
the hind feet, while it is smaller and darker in color than the 
Indian species. Both sexes also possess tusks, though those 
of the males are largest. All the Elephants feed upon vege¬ 
table matter. 


ORDERS OF MAMMALIA. 


305 



Fig. 152.—Skull of the Indian Elephant (Elephas Tndicus). i Tusk-like upper incisors; 
m Lower jaw. with grinding molars, but without incisors; n Nostrils, placed at the ex¬ 
tremity of the proboscis. 


Though there are now but two living species of Elephant, 
there is no doubt but that some of the fossil forms have died 
out since the appearance of man upon the globe. Of these, 
the best known is the Mammoth, frozen carcases of which 
have been found in the icy wilds of Siberia. 

Order IX. Carnivora (Lat. caro, flesh; voro , 1 devour).— 
The ninth order of Mammals is that of the Carnivora or Beasts 
of Prey, comprising the Lions, Tigers, Wolves, Dogs, Cats, 
Hymnas, Seals, Walruses, etc. The Carnivora are distin¬ 
guished by possessing two sets of teeth, which are simply 
enamelled, and are always of three kinds, incisors, canines, and 
molars, differing from one another in size and shape. The in¬ 
cisor teeth are generally six in each jaw; the canines are al¬ 
ways two in each jaw, and are much longer and larger than 
the other teeth. The molars are mostly cutting-teeth, fur¬ 
nished with sharp, uneven edges, but one or more of the hinder 
teeth have tuberculate crowns. The molars, too, graduate 






306 


VERTEBRATE ANIMALS. 


from a cutting to a tuberculate form as the diet is strictly car¬ 
nivorous or becomes more or less miscellaneous. 

The dental formula differs considerably in different mem¬ 
bers of the order, but subjoined is the dental formula of the 
Cats (. Pelidce ), which are the most typical examples of the 
Carnivora— 


i 3 _ - ; c -— 1 2 ; pm 3 — 3 ; m 1 — 1 = 30. 

3—3 1—1 2—2 1—1 


Besides the strictly flesh-eating dentition of the Carnivo¬ 
ra, the order is distinguished by always having the feet pro¬ 
vided with strong, curved claws, and the collar-bones (clavi¬ 
cles) are either quite rudimentary, or are altogether absent. 
The Carnivora are divided into the following three sections, 
founded upon the nature of the limbs : 



1. Pinnigrada (Fig. 153, B), in which both the fore and 
hind legs are short, and the feet form broad, webbed, swim¬ 
ming-paddles. The hind-feet are placed very far back, nearly 
in a line with the axis of the body, and they form with the 
hinder end of the body a powerful caudal fin. In this section 
are the Seals and Walruses. 

2. Plantigrada (Fig. 153, A), comprising the Bears, in 
which the whole, or nearly the whole, of the foot is applied to 
the ground, so that the animal walks upon the soles of the 
feet. 

3„ Digitigrada (Fig. 153, C), comprising the Cats, Lions, 



ORDERS OF MAMMALIA. 307 

Tigers, Dogs, etc., in which the heel is raised from the ground, 
and the animal walks upon tiptoe. 

The Seals and Walruses, forming the family Pinnigrada , 
are distinguished from the other Carnivora by their adapta¬ 
tion to an aquatic mode of life. In this respect they agree 
with the thoroughly aquatic Whales and Dolphins, but they 
differ from both the Cetacea and the Sirenia , not only in their 
dentition, but also in always having well-developed kind-limbs. 
The Seals (Fig. 154) are characterized by having incisor teeth 
in both jaws, at the same time that the canine teeth are not 
immoderately developed. They form a very numerous family, 
of which species are found in most seas out of the limits of 



Fig. 154. —Greenland Seal (Phoca Groenlandica). 


the tropics. They abound, however, especially in the seas of 
the Arctic and Antarctic regions. They are largely captured 
both for their oil and for their fur. The Walrus or Morse 
(Trichecus ) is distinguished from the true Seals by the fact 
that in the adult only two of the upper incisors are present; 
while the upper canines are enormously developed, and form 
two pointed tusks—fifteen inches or more in length—which are 
directed downward between the small lower canines, and pro¬ 
ject considerably below the chin. The Walrus is a large, 
heavy animal, from ten to fifteen feet in length, which is found 
in flocks in the Arctic seas, and is hunted both for its blubber 
and for the ivory of the tusks. 

The Plantigrade Carnivora apply the whole or the great¬ 
er part of the sole of the foot to the ground in walking; and 



308 


VERTEBRATE ANIMALS. 


this portion of the foot is nearly or altogether destitute of 
hairs, except in the White Bear. The most typical members 
of the Plantigrada are the Bears ( Ursidce ), of which the 
common Brown Bear and the White or Polar Bear are familiar 
examples. The Bears are much less purely carnivorous than 
the majority of the order, and, in accordance with their om¬ 
nivorous habits, the teeth do not exhibit the typical carnivo¬ 
rous characters. The incisors and canines have their usual car¬ 
nivorous form, but the praemolars and molars are furnished 
with broad tubercular crowns. The claws are large, curved, 
and strong, but are not retractile. The tongue is smooth, the 
ears small and erect, the tail short, the nose mobile, and the 
pupil circular. Most of the Bears are only carnivorous, in so 
far that they eat flesh when they can get it; but a great part 
of their food consists of roots, acorns, honey, and even insects. 
Nearly related to the true Bears are the familiar Raccoons 
{Procyomi) of America, the Coatis {JSfasua) of South America, 
and the Wah ( Ailurus ) of India. 

The only remaining Plantigrades of importance are the 
Badgers ( Meles ) of Europe, Asia, and America, the Gluttons 
or Wolverines ( Gulo ) of the same continents, and the Honey- 
badgers (Mellivora) of Africa. 

Forming a kind of transition between the Plantigrada and 
the Digitigrada is a group of Carnivora which comprises nu¬ 
merous forms, such as the Weasels, Otters, and Civets, which 
apply part, but not the whole, of the sole of the foot to the 
ground. 

The Weasels ( Mustelidae ) have short legs and elongated, 
worm-like bodies, with a stealthy, gliding mode of progression. 
Good examples are the Pole-cat, the Mink, the Ermine, and 
the Sable. The two latter furnish the beautiful and valuable 
furs known by their names. Here also belongs the Skunk 
{Mephitis), celebrated for its intensely disagreeable odor when 
alarmed or irritated. The Otters are nearly allied to the 
Weasels, but have webbed feet adapted for swimming. The 
great Sea-otter yields a very valuable fur. The Civets and 
Genettes ( Viverridce) all belong to the Old World. The true 
Civet-cat inhabits North Africa, and is furnished with a pouch 
which secretes the peculiar fatty substance which is used as a 
perfume under the name of “ civet.” 

The typical group of the Carnivora is that of the Digiti¬ 
grada, comprising the three tribes of the Dogs ( Canidce ), the 
Hyaenas {Mycenidce), and the Cats {Felidae). The family 
CanidcB comprises the true Dogs, the Wolves, the Foxes, and 


ORDERS OF MAMMALIA. 


309 


the Jackals, all characterized by their pointed muzzles, smooth 
tongues, and non-retractile claws, and by the fact that the 
fore-feet have five toes, while the hind-feet have only four. In 
the IlycenidcB , comprising the Hya?nas r there are only four 
toes to all the feet, the muzzle is rounded, the tongue is rough, 
and the hind-legs are shorter than the fore-legs. The Hyaenas 
are ill-conditioned, ferocious animals, which occur in Africa, 
Asia Minor, Arabia, and Persia. 

The most highly carnivorous, and therefore the most typi¬ 
cal, group of the Carnivora is that of the Cats or Felidae , 
comprising the Lions, Tigers, Leopards, Panthers, Cats, and 
others. In all these the animal w T alks lightly upon the tips of 
the toes, and the soles of the feet are hairy. The jaws are 
short, and, owing to this and to the great size of the muscles 
which move the lower jaw, the head assumes a rounded form, 
with a short muzzle. The molars and praemolars are fewer in 
number than in any other of the Carnivora —hence the short¬ 
ness of the jaws; and they are all furnished with cutting- 
edges, except the last molar in the upper jaw, which is tuber- 
culate. The legs are nearly of equal length, and the hind-feet 
have only four toes, wdiile the fore-feet have five toes each. 
All the toes are furnished with strong, curved, retractile claws, 
which, when not in use, are withdrawn within sheaths by the 
action of elastic ligaments. The tongue is armed with horny 
eminences, which render it rough and prickly, and adapt it for 
the office of licking flesh from the bones of the prey. They 
are all extremely light upon their feet, and excessively muscu¬ 
lar ; and all have the habit of seizing their prey by suddenly 
springing upon it. In this section are the Lion (Felis leo ), the 
Tiger [Felis Tigris ), the Jaguar (Felis onca ), the Puma [Felis 
concolor ), the Leopard [Felis leopardus ), the Lynxes, and the 
true Cats. 

The Lions are entirely confined to the Old World, inhabit¬ 
ing Southern Asia and Africa. The males are maned, and the 
tail is tufted. The Royal Tiger is exclusively Asiatic, as are 
most of the Tiger-cats, but some of the latter are American. 
The Spotted Cats or Leopards are represented, among others, 
by the Leopard and Cheetah of the Old World, and the w r ell- 
known Jaguar of the American Continent. The Puma is also 
American, but its color is uniform. The Lynxes are distin¬ 
guished by their tufted ears, and are found both in the Eastern 
and Western hemispheres. 

Order X. Rodentia (Lat. rodo, I gnaw).—In this order 


310 


VERTEBRATE ANIMALS. 


are a number of small animals, characterized by the absence 
of canine teeth, and the possession of two long curved incisor 
teeth in both jaws, which are separated by a wide interval 
from the molars (Fig. 155). There are seldom more than two 



Fig. 155.—A, Skull of the Beaver (after Owen); B, Diagram of one of the incisor teeth 
of a Rodent, showing the chisel-shaped point, a Enamel; d Soft tooth-substance 
(dentine). 


incisors in the upper jaw (sometimes four), but there are never 
more than two in the lower jaw. The molar teeth are few in 
number (rarely more than four on each side of each jaw). The 
feet are usually furnished with five toes each. 

The most characteristic point about the Rodents is to be 
found in the structure of the incisor teeth, which are adapted 
for continuous gnawing. They grow from persistent pulps, 
and consequently continue growing as long as the animal lives. 



Fig. 156.—Hamster (Gricetm vulgaris). 


They are large, long, and curved, and are covered in front with 
a layer of hard enamel, so that the softer parts of the tooth 












ORDERS OF MAMMALIA. 


311 


are placed behind (Fig. 155, B). The result of this is, that 
as the tooth is used in gnawing, the softer parts behind wear 
away more rapidly than the hard enamel in front, and thus the 
crown of the tooth acquires by use a chisel shape, bevelled 
away behind, and the enamel forms a persistent cutting-edge. 
The Rodents are almost all of small size, and are very prolific. 
They subsist principally, if not entirely, on vegetable matters, 
especially the harder parts of plants, such as the bark and 
roots. Many possess the power of building very elaborate 
nests, and most of them hybernate (i. e ., remain torpid through¬ 
out the winter). They are very generally distributed over the 
whole world. 

The order JRodentia comprises a large number of families, 
of which little more than the names can be mentioned. The 
most important families of Rodents are the following: 1. Ae- 
poridce y comprising the Hares and Rabbits. The Hares gen¬ 
erally occur in temperate regions, but some are African, and 
one species occurs in the Arctic regions, while the common 
American Hare ( Lepus Americanus ) extends from Canada to 
Mexico. 2. Gavidce , comprising the Capybaras, Guinea-pigs, 
etc. The Capybara is the largest of living Rodents, and is 
not unlike a small pig. It- is a native of South America, 
and leads an amphibious life. Here also belong the Agoutis 
(Dasyprocta ) of South America and the West Indies, and the 
Pacas of South America. 3. Ilystricidce , comprising the Por¬ 
cupines, and characterized by the fact that the body is covered 
with longer or shorter spines or quills mixed with bristly hairs. 
Most of the Porcupines live in burrows, and are much like the 
Rabbits in their habits, but some are furnished with prehen¬ 
sile tails, and live in trees. 4. Castoridce or Beaver family, 
comprising the Beaver, Musquash, and Coypu. The Beaver 
has webbed feet and a scaly tail, and the fur is an article of 
considerable value. It inhabits both North America and 
Europe. The Musquash resembles the Beaver in many re¬ 
spects, and is also a native of Northern America; but the 
Coypu is South American. 5. Muridoz , comprising the Mice, 
Rats, Hamster (Fig. 156), Lemmings, etc. The Rats and 
Mice are too well known to require more than merely to be 
mentioned. 6. Dijiodidce, comprising the Jerboas of the Old 
World, and the Jumping Mice of America. 7. Myoxidce, com¬ 
prising the Dormice, which must not be confounded with the 
true Mice on the one hand, or with the Shrew-mice on the 
other hand. 8. Sciuridce , comprising the Squirrels, Ftying 
Squirrels, and Marmots. The Flying Squirrels do not really 


312 


VERTEBRATE ANIMALS. 


fly, but, like the “ flying ” Phalangers, they take long leaps 
from tree to tree by means of laterally-extended folds of skin. 
The Marmots, unlike the typical Squirrels, are ground-animals, 
and live in burrows. An excellent example is afforded by the 
Prairie-dog ( Arctomys Ludovicianus) of North America. 

Order XI. Cheiroptera (Gr. cheir , hand; pteron , wing). 
—This order is undoubtedly one of the most natural and dis¬ 



tinctly circumscribed orders in the whole class of the Mam¬ 
malia, comprising only the Bats. In many respects, however, 
it might be well to regard the order as merely a modified 
branch of the Insectivora , just as the Pinnigrada are regard¬ 
ed as a modified offshoot of the Carnivora . The Cheiroptera 
or Bats are essentially characterized by the fact that the fore¬ 
limbs are much longer than the hind-limbs, and have several of 
the fingers enormously elongated. These enormously length¬ 
ened digits are united by an expanded leathery membrane or 
“ patagium,” which not only stretches between the fingers, 
but is also extended between the fore and hind limbs, and is 
attached to the sides of the body (Fig. 157). The patagium 









ORDERS OF MAMMALIA. 


313 


thus formed often includes the tail, and is nearly or quite 
naked or destitute of hairs on both sides. It is used as an 
organ of true flight, and, in accordance with this, there are 
well-developed collar-bones (clavicles), and the breastbone is 
furnished with a ridge for the attachment of the pectoral mus¬ 
cles. Of the fingers of the hand at least three are destitute 
of nails. The mammary glands are placed upon the chest. 
Teeth of three kinds are always present, and the canines are 
always well developed. 

The Bats are all twilight-loving or nocturnal animals, and 
they are the only Mammals which possess the power of true 
flight, though several others can make extended leaps from 
tree to tree. The eyes are small, but the ears are very large, 
and their sense of touch is most acute. During the day they 
retire to caves or crevices in rocks, where they suspend them¬ 
selves by the short thumbs, which are provided with claws. 
In their flight, though they can turn with great ease, they are 
by no means as rapid and active as the true Birds. The tail 
is sometimes very short, sometimes moderately long, and is 
usually included in a continuation of the “ patagium,” which 
extends between the hind-legs. The body is covered with 
hair, but the patagium is usually nearly or quite hairless. 
Most of the Bats hybernate. 

The Cheiroptera are conveniently divided into the two 
sections of the Insectivorous and Frugivorous Bats. In the 
first section are all the bats of temperate climates, most of 
which are of very small size, and all of which live upon in¬ 
sects. Here also belong the great Vampire-bats ( Phyllosto- 
midoe) of South America. In the second, or fruit-eating sec¬ 
tion of the Cheiroptera , are only the Fox-bats {Pteropidee ), 
which are especially characteristic of the Pacific Archipelago, 
inhabiting Australia, Java, Sumatra, Borneo, etc., but occur¬ 
ring also in Asia and Africa. They are among the largest 
of the Bats, one species—the Pteropus edulis or Kalong—at¬ 
taining a length of from four to five feet from the tip of one 
wing to the tip of the other. 

Order XII. Insectivora (Lat. insectum , an insect; voro, 
I devour).—The twelfth order of Mammals is that of the In- 
sectivora , which comprises a number of small animals, very 
similar in many respects to the Rodents, but wanting the 
peculiar incisors of that order, and also being provided with 
clavicles. All the three kinds of teeth are present, but the 
dentition is very various, and the only common character is 


314 


VERTEBRATE ANIMALS. 


that the crowns of the molar teeth are furnished with small 
pointed eminences or cusps, adapted for crushing insects. All 
the toes have claws, there are usually five toes to each foot, 
and most of the Insectivora are plantigrade , that is to say, 
walk upon the soles of the feet. They are all ^mall, and they 
exist over the whole world, except in Australia and South 
America, where their place is taken by Marsupials, such as the 
Opossums. 

The Insectivora are divided into the three families of the 
Moles ( Talpidoe ), the Shrews (Soricidoe) , and the Hedgehogs 
(Erinaceidce ). The Moles (Fig. 158) are distinguished by 



Fig. 158.—Insectivora. Mole (Talpa Europma). 


having the body covered with hair, the feet short and formed 
for digging, and the toes furnished with strong, curved claws. 
There is no external ear, and the eyes are either extremely 
small, or are completely concealed beneath the fur. They are 
all nocturnal burrowing animals. The Star-nosed Moles ( Gon- 
dylurci) are American, but their habits are like those of the 
European Mole ( Talpa Europeea , Fig. 158). The Golden 
Moles ( Chrysochloris) are African, and are remarkable for the 
iridescence of their fur. The Shrews are very like the true 
Mice in external appearance, but they are really widely dif¬ 
ferent. The body is covered with hair, the feet are not adapted 
for digging, and there are mostly external ears, while the eyes 
are well developed. No division of the Insectivora is more 
abundant or more widely distributed than the Soricidce, and 
one of the Shrews is probably the smallest of existing Mam¬ 
mals, not exceeding two and a half inches in length, counting 
in the tail. Besides the true Shrews ( Sorex ), this family in¬ 
cludes also the Elenhant Shrews ( Macroscelides ) of Africa, 
and the common Water-mole ( Scalops aquations) of North 









ORDERS OF MAMMALIA. 


315 


America. The third family includes only the well-known 
Hedgehogs, which have the power of rolling themselves into 
a ball at the approach of danger, and which have the upper 
surface of the body covered with short prickly spines, forming 
a protective armor. The common European Hedgehog (Eri- 
naceus Europoeus) is the type of the family, but other species 
occur in Africa and India. The “ Tenrecs ” ( Centetes) of 
Madagascar are closely allied to the Hedgehogs, but have no 
power of rolling themselves up. The “ Banxrings ” ( Tupaia ) 
of the Indian Archipelago have a long, compressed tail, and live 
mostly in trees. 

Before passing on to the next order, a few words must be 
said about a curious transitional form, which has been alter¬ 
nately placed in the Cheiroptera , the Insectivora , or the 
Quadrumana , or has been regarded as the type of a separate 
order. The animal alluded to is the so-called Flying Lemur 
(Galeopithecus volitans ), of which more than one species is 
known as inhabiting the Indian Archipelago. The leading 
characteristic in this singular animal is the possession of a Jly- 
ing-membrane, which extends as a broad expansion from the 
nape of the neck to the arms, from the arms to the hind-legs, 
and from the hind-legs to the tail. The fingers are not elon¬ 
gated, and do not support a “ patagium,” so that the animal 
has no power of true flight, but can simply take extended 
leaps from tree to tree. The Galeopithecus lives chiefly upon 
small insects and birds, and it should, probably, be regarded 
as an aberrant form of the Insectivora. 

Order XIII. Quadrumana (Lat. quatuor , four; manus , 
hand).—The thirteenth order of Mammals is that of the Quad¬ 
rumana, comprising the Apes, Monkeys, Baboons, and Le¬ 
murs. The characteristic of this order is that the innermost 
toe (great-toe) of the hind-limbs can be opposed to the other 
toes, so that the hind-feet become prehensile hands. The term 
“ opposed ” simply implies that the toe can be so adjusted, as 
regards the extremities of the other toes, that any object can 
be grasped between them, just as the thumb of the human 
hand can be “ opposed ” to any of the fingers. The fore-feet 
may be destitute of a thumb, but, when this is present, it too 
is generally opposable to the other digits, so that the animal 
becomes truly four-handed or “ quadrumanous.” 

The Quadrumana are divided into three very natural sec¬ 
tions, separated from one another both by their anatomical 
characters and their geographical distribution. 


316 


VERTEBRATE ANIMALS. 


Section A. Strepsirhina. —Characterized by having the 
nostrils twisted or curved, and placed at the end of the nose, 
while the second toe of the hind-feet is furnished with a claw. 
The Quadrumana of this section are chiefly referable to Mada¬ 
gascar as their geographical centre, but they spread from 
Madagascar westward into Africa, and eastward to the Indian 
Archipelago. In this family are the Aye-Aye ( Cheiromys ), 
the Loris and Slow Lemurs (Nycticebidaz), and the Lemurs 
(Lemuridoe ). The Aye-Aye is confined to Madagascar, and is 
not unlike a large squirrel in appearance, having a long bushy 
tail. The incisors grow from permanent pulps, like those of 
Rodents, and there are no canines. The Loris and Slow Le¬ 
murs have either no tail or a rudimentary one, and they are 
confined to Southern Asia, and the great islands of the Indian 
Archipelago. The true Lemurs are natives of Madagascar, 
and are often spoken of as “ Madagascar cats.” They have a 
soft, woolly fur, and a long tail, which is prehensile. The sec¬ 
ond toe of the hind-foot has a long and pointed claw. 

Section B. JPlatyrhina. —This section includes those mon¬ 
keys in which the nostrils are simple, and are placed far apart; 
the thumbs of the fore-feet are wanting, or, if present, are not 
opposable; and the tail is generally prehensile. The Platy- 
rhine Monkeys are exclusively confined to South America, oc¬ 
curring especially in Brazil, and they are all adapted for a more 
or less purely arboreal life. The best-known members of this 
section are the Marmosets (Hapalidce), and the great family 
of the Cebidce, comprising the Spider-monkeys, the Howlers, 
and others. The Howlers ( Mycetes ) are remarkable for having 
a bony drum at the summit of the windpipe, by which the 
voice is rendered extraordinarily resonant, and peculiarly weird 
and terrifying to those who hear it. 

Section C. Catarhina. —In this, the highest section of the 
Quadrumana , the nostrils are oblique and placed close to¬ 
gether, and the thumbs of all the feet are opposable, so that 
they are truly “ quadrumanous.” The dental formula agrees 
with that of man : 


. 2—2 1—1 
* 2 — 2 ; ° 1 — 1 ; 


2—2 3—3 

^2=3^ 3-3 = 33 


The incisor teeth, however, are prominent and projecting, 
and the canines, especially in the males, are large and j)ointed, 
while the teeth form an uneven series. The tail is never pre¬ 
hensile, and is sometimes absent. Cheek-pouches are often 


ORDERS OF MAMMALIA. 


317 


present. In one single instance ( Colobus) the thumbs of the 
fore-limbs are wanting. 



Fig. 159. —Quadrumana. Green Monkey (Cercocebus sabceus). (After Cuvier.) 


With the single exception of a Monkey which occurs on 
the Rock of Gibraltar, all the Catarhine Monkeys are confined 
to Africa and Asia. The most typical forms of the section are 
the Serruiopitheci and Macaques of Asia. Less typical are 
the Baboons, which inhabit Africa, and are among the most re¬ 
pulsive of all the Quadrumana. In these the tail is always 
short, and often quite rudimentary. The head is large, and 
the muzzle greatly prolonged, having the nostrils at its ex¬ 
tremity. More than any other of the Monkeys they employ 
the fore-limbs in terrestrial progression, running upon all fours 
with the greatest ease. 

The third family of the Catarhine Monkeys is that of the 
Anthropoid Apes, so called from their making a nearer ap¬ 
proach to man in anatomical structure than is the case with 
any other Mammal. The Anthropoid Apes are distinguished 
by having no tail, nor cheek-pouches. The hind-limbs are 
short—shorter than the fore-limbs—and the animal can pro¬ 
gress in an erect or semi-erect posture. At the same time the 
hind-feet are strictly prehensile, since the thumbs are oppos- 


318 


VERTEBKATE ANIMALS. 


able to tbe other toes. The canine teeth of the males are 
very long, strong, and pointed, but this is not the case in the 
females. 

In this tribe are the Gibbons, the Chimpanzee, the Orang¬ 
outang, and the Gorilla. The Gibbons form the genus Hylo- 
bates , and they belong to Asia, India, and the Indian Archi¬ 
pelago. The anterior limbs in these monkeys are extremely 
long, and the hands nearly or quite touch the ground when 
the animal stands erect. The Orang-outang ( Simia ) has no 
cheek-pouches, and the hips are covered with hair. The arms 
are of excessive length, and the hind-legs very short. When 
young, the head of the Orang-outang is not very different from 
that of a child, but, as the animal grows, the bones of the face 
gradually lengthen, while the skull remains much about the 
same; great bony ridges are developed for the attachment of 
the muscles which act upon the jaws; the incisors project; 
the canine teeth of the males become long and pointed, till 
ultimately the muzzle becomes as pronounced and well marked 
as in the Carnivorous animals (Fig. 160, A). The best-known 




Fig. 160.—A, Skull of the Orang-outang; B, Skull of a European adult. 


species of Orang is the Simla Satyrus , which inhabits Suma¬ 
tra, Borneo, and the other larger islands of the Indian Archi¬ 
pelago; but there are probably other species or varieties. 
The Chimpanzee and Gorilla both belong to Africa, and form 
the genus Troglodytes. The Chimpanzee is a native of West¬ 
ern Africa, and has the arms much shorter proportionately 
than in the Gibbons and Orangs. Still they are much longer 




ORDERS OF MAMMALIA. 


319 


than the hind-limbs, and reach below the knees. The hands 
are naked to the wrist, and the face is also naked and much 
wrinkled. The Gorilla is in most respects like the Chimpan¬ 
zee, but is much larger, attaining a height of fully five feet. 
It is a native of Lower Guinea and Equatorial Africa, and is 
enormously strong and very ferocious. It is now generally 
looked upon as the highest of the Anthropoid Apes. 

Order XIV. Bimaha (Lat. bis , twice; manus , hand).— 
In this order stands Man alone, and little, therefore, needs to 
be said on this head. Man is distinguished zoologically from 
all other Mammals by his habitually erect posture and pro¬ 
gression upon two legs. The lower limbs are exclusively de¬ 
voted to progression and to supporting the weight of the body. 
The fore-limbs are shorter than the legs, and have nothing to 
do with progression. The thumb can be opposed to the other 
fingers, and the hands are therefore prehensile. The fingers 
and toes are furnished with nails ; but the innermost digit of 
the foot (the great-toe) is not capable of being opposed to the 
other toes, so that the foot is useless as a grasping organ. 
The foot is broad and plantigrade, the whole sole being ap¬ 
plied to the ground in walking. 

The teeth are thirty-two in number, and they form q, nearly 
even and uninterrupted series, without any gap or interval. 
The dental formula is : 




The brain is more largely developed, and more richly furnished 
with large and deep foldings or convolutions, than is the case 
in any other Mammal. Lastly, Man is the only terrestrial 
Mammal in which the body is not furnished with a general 
covering of hair. 

The purely anatomical distinctions between Man and the 
other Mammals are thus seen to be not very striking, and of 
themselves they would hardly entitle Man to the position of 
more than a distinct order in the class Mammalia. When, 
however, we take into account the vast and unsurmountable 
mental differences, both intellectual and moral, between Man 
and the highest of the brutes, and when we reflect that this 
mental difference must have some physical correspondence, 
it becomes a question whether the group Bimana should 
not have the value of a distinct sub-kingdom, while there 


320 


VERTEBRATE ANIMALS. 


can be little hesitation in giving Man at least a class to 
himself. 

In the words of Dr. Pritchard, “ the sentiments, feelings, 
sympathies, internal consciousness, and mind, and the habi¬ 
tudes of mind and action thence resulting, are the real and 
essential characteristics of humanity.” 


GLOSSARY 


Ab-do'men (Lat. cibdo, I conceal). The posterior cavity of the body, contain¬ 
ing the intestines and others of the viscera. In manv Invertebrates there is 
no separation of the body-cavity into thorax and abdomen, and it is only in 
the higher Annulosa that a distinct abdomen can be said to exist. 

Ab-er'rant (Lat. aberro , I wander away). Departing from the regular type. 

Ab-nob'mal (Lat. ab , from ; norma , a rule). Irregular; deviating from the 
ordinary standard. 

Ab-o-ma'sum. The fourth cavity of the complex stomach of the Ruminants. 

A-branch'i-ate (Gr. a, without; bragchia , gills). Destitute of gills or bran¬ 
chiae. 

A-ca-le'ph^. (Gr. akalephe , a nettle). Applied formerly to the Jelly-fishes or 
Sea-nettles, and other Radiate animals, in consequence of their power of 
stinging, derived from the presence of microscopic cells, called “ thread- 
cells,” in the integument. 

A-c an -tho-ceph'a-la (Gr. akantha , a thorn ; kephale , head). A class of para¬ 
sitic worms in which the head is armed with spines. 

A-can-tho-me-tri'na (Gr. akantha ; and metra , the womb). A family of Pro¬ 
tozoa, characterized by having radiating siliceous spines. 

A-can-tho-pter-yo'-i-i (Gr. akantha , spine; pterux , wing). A group of bony 
fishes with spinous rays in the front part of the dorsal fin. 

A-car'i-na (Gr. akari , a mite). A division of the Arachnida , of which the 
Cheese-mite is the type. 

Ac-cre'tion. 

A-ceph'a-lous (Gr. a , without; kephale , head;. Not possessing a distinct 
head. 

A-ce-tab'u-la (Lat. acetabulum , a cup). The suckers with which the cephalic 
processes of many Cephalopoda (Cuttle-fishes) are provided. 

A-ce-tab'u-lum. The cup-shaped socket of the hip-joint in Vertebrates. 

Ao'ri-ta (Gr. akritos , confused). A term sometimes employed as synony¬ 
mous with Protozoa or the lowest division of the animal kingdom. 

Ao-ti-nom'eres (Gr. aktin, a ray; meros , a part). The lobes which are 
mapped out on the surface of the body of the Ctenophora, by the cteno- 
phores, or comb-like rows of cilia. 

Ao-tin-o-so'ma (Gr. aktin; and soma, body).. Employed to designate the 
entire body of any Actinozoon, whether this be simple (as in the Sea- 
anemones), or composed of several zooids (as in most Corals). 

Ac-txn-o-zo'a (Gr. aktin ; and zoon, an animal). That division of the Coden- 
terata of which the Sea-anemones may be taken as the type. 

Ad-el-ar-thro-so'ma-ta (Gr. adelos , bidden; arthros, joint; soma, body). 
Ad order of the Arachnida. 

Ad-duo'tor. 

A-e'ri-al. 

A-oam'io (Gr. a, without; gamos , marriage). Applied to all forms of repro¬ 
duction in which the sexes are not directly concerned. 



322 


GLOSSARY. 


A l-lan-toid'e-a. The group of Vertebrata in which the foetus is furnished 
with an allantois, comprising the Reptiles^ Birds, and Mammals. 

Al-lan-tois' (Gr. alias , a sausage). One of the “membranes” of the foetus 
in certain Vertebrates. 

Al-ve'o-ei (Lat. dim. of alms, belly). Applied to the sockets of the teeth. 

Am-bu-la'cra (Lat. ambulacrum , a place for walking). The perforated spaces 
or “avenues” through which are protruded the tube-feet, by means of 
which locomotion is effected in the Echinodermata. 

Am'bu-la-to-ry (Lat. ambulo , I walk). Formed for walking. Applied to a 
single limb, or to an entire animal. 

A-met-a-bol'ic (Gr. a, without; metabole , change). Applied to those insects 
which do not posses's wings when perfect, and which do not, therefore, pass 
through any marked metamorphosis. 

Am'ni-on (Gr. amnos , a lamb). One of the foetal membranes of the higher 
V ertebrates. 

Am-ni-o'ta. The group of Vertebrata in which the foetus is furnished with 
an amnion, comprising the Reptiles, Birds, and Mammals. 

A-mce'ba (Gr. amoibos , changing). A species of Rhizopod, so called from the 
numerous changes of form which it undergoes. 

A-m<e'bi-form. Resembling an Amoeba in form. 

A-mor-pho-zo'a (Gr. a, without; morphe , shape; zoiin, animal). A name some¬ 
times used to designate the Sponges. 

A-mor'phous. 

Am-phib'i-a (Gr. amphi , both; bios , life). The Frogs, Newts, and the like, 
which have gills when young, but can always breathe air directly when adult. 

Am-phi-c(e'lous (Gr. amphi, at both ends; icoilos , hollow). Applied to ver¬ 
tebrae which are concave at both ends. 

Am'phi-discs (Gr. amphi, at both ends ; dislcos, a quoit, or round plate). The 
spicula which surround the gemmules of Spongilla , and resemble two 
toothed wheels united by an axle. 

Am-phi-ox'us (Gr. amphi, at both ends; oxus, sharp). The Lancelet, a little 
fish, which alone constitutes the order Pharyngobranchii. 

Am-phi-pneus'ta (Gr. amphi ? both : pneo, I breathe). Applied to the “ pe- 
rennibranchiate ” Amphibians which retain their gills through life. 

Am-phip'o-da (Gr. amphi ; and pous, a foot). An order of Crustacea. 

A'nal (Lat. anus, the vent). Connected with the anus, or situated near the 
anus. 

An-al-lan-toid'e-a. The group of Vertebrata in which the embryo is not 
furnished with an allantois. 

A-nal'o-gous. Applied to parts which perform the same function. 

An-am-ni-o'ta. The group of Vertebrata in which the embryo is destitute of 
an amnion. 

An-arth-rop'o-da (Gr. a, without; arthros , a joint; pous, foot). That divi¬ 
sion of Annulose animals in which there are no articulated appendages. 

Anch-y-lo'sis or Ank-y-lo'sis (Gr. ankulos, crooked). The union of two 
bones by osseous matter, so that they become one bone, or are immovably 
joined together. 

An-drog'y-nous (Gr. aner, a man ; gune, a woman). Synonymous with her¬ 
maphrodite, and implying that the two sexes are united in the same indi¬ 
vidual. 

An'dro-phores (Gr. aner, a man ; and phero, I carry). Applied to medusiform 
gonophores of the Hydrozoa , which carry the spermatozoa, and differ in 
form from those in which the ova are developed. 

An-nel'i-da (a Gallicised form of Annulata). The Ringed Worms, which 
form one of the divisions of the Anarthropoda. 

An'nu-la-ted. Composed of a succession of rings. 

An-nu-loi'da (Lat. annulus, a ring; Gr. eidos, form). The sub-kingdom 
comprising the Echinodermata and the Scolecida (= Echinozoa). 

An-nu-lo'sa (Lat. annulus). The sub-kingdom comprising the Anarthropoda 
and the Arthropoda or Articulata, in all of which the body is more or less 
evidently composed of a succession of rings. 


GLOSSARY. 


323 


An-o-mo-don'ti-a (Gr. anomos, irregular; odous, tooth). An extinct order of 
Reptiles, often called Dicynodontia. 

An-o-mc'ra (Gr. anomos , irregular; our a, tail). A tribe of Decapod Crusta¬ 
cea ,, of which the Hermit-crab is the type. 

An-o-plu'ra (Gr. anoplos, unarmed; our a, tail). An order of Apterous Insects. 

A-nou'ra (Gr. a, without; oura, tail). The order of Amphibia comprising 
the Frogs and Toads, in which the adult is destitute of a tail. Often called 
Matrachia. 

An-ten'n^: (Lat. antenna , a yard-arm). The jointed homs or feelers pos¬ 
sessed by the majority of the Articulata. 

An-ten'nules (dim. of antennae). Applied to the smaller pair of antenncc in 
the Crustacea. 

An'thro-poid. 

An-ti-bra'chi-tjm (Gr. anti , in front of; brachion , the arm). The fore-arm 
of the higher Vertebrates, composed of the radius and ulna. 

Ant'lers. Properly the branches of the homs of the Deer tribe ( Cervida), 
but generally applied to the entire homs. 

An'tli-a (Lat. antlia , a pump). The spiral trunk or proboscis with which 
Butterflies and other Lepidopterous Insects suck up the juices of flowers. 

Aph-a-nip'te-ra (Gr. aphanos , inconspicuous; pteron , a wing). An order of 
Insects comprising the Fleas. 

Ap-la-cen-taxi-a. The section of the Mammalia, comprising the two divisions 
of the Didelphia and Monodelphia , in which the young is not furnished 
with a placenta. 

Ap'o-da (Gr. a, without; nodes , feet). Applied to those fishes which have no 
ventral fins. Also to the footless Ccecilice among the Amphibia. 

Ap'o-dal. Devoid of feet. 

Ap-o-dem'a-ta (Gr. apodaio, I portion off). Applied to certain chitinous 
septa which divide the tissues in Crustacea. 

Ap'te-ra (Gr. a, without; pteron , a wing). A division of Insects, which is 
characterized by the absence of wings in the adult condition. 

Ap'ter-ous. Devoid of wings. 

Ap'ter-yx (Gr. a, without; pterux, awing). A wingless bird of New Zea¬ 
land, belonging to the order Cur sores. 

A-quat'io. 

A-quif'e-rous. 

A-rach'ni-da (Gr. arachne, a spider). A class of the Articulata, comprising 
Spiders, Scorpions, and allied animals. 

Ar-a-ne'i-da. 

Ar-bo-res'cent. Branched like a tree. 

Ar-chx-op'te-ryx (Gr. archaios, ancient; pterux, wing). The singular fossil 
bird which alone constitutes the order of the Saururce. 

Arch-en-ceph'a-la (Gr. archo, I overrule; eglcephalos, brain). The name 
applied by Owen to his fourth and highest group of Mammalia , compris¬ 
ing Man alone. 

Ar-e-na'ce-ous. Sandy, or composed of grains of sand. 

Ar-throp'o-da . 

Ar-tic-u-la'ta (Lat. articulus, a joint). A division of the animal kingdom, 
comprising Insects, Centipedes, Spiders, and Crustaceans, characterized by 
the possession of jointed bodies or jointed limbs. Tte term Arthropoda is 
now more usually employed. 

Ar-ti-o-dac'ty-la (Gr. artios , even; daJctulos , a finger or toe). A division 
of the hoofed quadrupeds ( Ungulata) in which each foot has an even num¬ 
ber of toes (two or four). 

As-cid-i-oi'da (Gr. aslcos, a bottle; eidos, a form). A synonym of Tunicata, a 
class of Molluscous animals, which have the shape, in many cases, of a two¬ 
necked bottle. 

A-sex'u-al. Applied to modes of reproduction in which the sexes are not 
concerned. 

A-siph'o-kate. Not possessing a respiratory tube or siphon. (Applied to a 
division of the LamelUbranchiate Molluscs.) 


324 


GLOSSARY. 


As'ter-oid (Gr. aster, a star; and eidos, form). Star-shaped, or possessing 
radiating lobes or rays like a star-fish. 

As-te-roid'e-a. An order of Echinodermata , comprising the Star-fishes, 
characterized by their rayed form. 

A-stom'a-totjs (Gr. a, without; stoma, mouth). Not possessing a mouth. 

At'las (Gr. the god who holds up the heavens). The first vertebra of the neck, 
which articulates with and supports the skull. 

A'tri-um (Lat. for a hall). Applied to the great chamber or “ cloa'ca,” into 
which the intestine opens in the Tunicata. 

Au-rel'la (Lat. aurum, gold). Applied to the chrysalides of some Lepidop- 
tera, on account of their exhibiting a golden lustre. 

Au'ri-cle (Lat. dim. of auris, ear). Applied to one of the cavities of the 
heart, by which blood is driven into tne ventricle. 

Au-toph'a-gi (Gr. autos, self; phago, I eat). Applied to birds whose young 
can run about and obtain food for themselves as soon as they escape from 
the egg. 

A'ves (Lat. avis , a bird). The class of the Birds. 

Av-i-cu-la'ri-um (Lat. avicula, dim. of avis, a bird). A singular appendage, 
often shaped like the head oi a bird, found in many of the Polyzoa. 

Axis (Gr. axon, a pivot). The second vertebra of the neck, upon which the 
skull and atlas usually rotate. 

Az'y-gos (Gr. a, without; zugon, yoke). Single; without a fellow. 

Bac-te'ri-tjm (Gr. balder ion, a staff). A kind of staff-shaped filament which 
appears in organic infusions after they have been exposed to the air. 

Bal'an-cers. 

Ba-lan'i-d.e (Gr. balanos, an acorn). A family of sessile Cirripedes, com¬ 
monly called “ Acorn-shells.” 

Ba-leen' (Lat. baloena, a whale). The horny plates which occupy the palate 
of the true or “ whale-bone” Whales. 

Bat'i-des (Gr. batos, a bramble). The family of the Elasmobranchii , com¬ 
prising the Bays. 

Ba-tra'chi-a (Gi\ batrachos, a frog). Often loosely applied to any of the 
Amphibia, but sometimes restricted to the Amphibians as a class, or to the 
single order of the Anoura. 

Bi'fid (Lat. bis, twice; jindo, I cleave). Cleft into two parts ; forked. 

Bi-lat'er-al (Lat. bis, twice ; latus, a side). Having two symmetrical sides. 

Bi-ma'na (Lat. bis , twice; manus, a hand). The order of Mammalia compris¬ 
ing Man alone. 

Bip'e-dal (Lat. bis, twice; pes, foot). Walking upon two legs. 

Bi-ra'mous (Lat. bis, twice; ramus, a branch). Applied to a limb which is 
divided into two branches (e. g., the limbs of Cirripedes). 

Bi 'valve (Lat. bis, twice; valvce, rolding-doors). Composed of two plates or 
valves; applied to the shell of the Lamellibranchiata and Brachiopoda , and 
of the carapace of certain Crustacea. 

Blas-toid'e-a (Gr. blastos , a bud; and eidos, form). An extinct order of Echi¬ 
nodermata, often called Pentremites. 

Braoh-i-op'o-da (Gr. brachion, an arm; pous, the foot). A class of the Mol- 
luscoida, often called “Lamp-shells,” characterized by possessing two 
fleshy arms continued from the sides of the mouth. 

Bra'chi-dm (Gr. brachion, arm). Applied to the upper arm of Verte¬ 
brates. 

Brach-y-u'ra (Gr. brachus, short; our a, tail). A tribe of the Decapod Crus¬ 
taceans with short tails ( i . e., the Crabs). 

Bracts. (See Hydrophyllia.) 

Brad-y-pod'i-d^ (Gr. bradus, slow; podes, feet). The family of Edentata 
comprising the Sloths. 

Branch'i-a (Gr. bragchia, the gills of fishes). A respiratory organ adapted to 
breathe air dissolved in water. 

Branch'i-ate. Possessing gills or branchife. 

Bran-chif'e-ra (Gr. bragchia, gills; and phero, I carry). A division of Gas- 


GLOSSARY. 


325 


teropodous Molluscs, in •which the respiration is aquatic, and the respi¬ 
ratory organs are mostly in the form of distinct gills. 

Branch-i-o-gas-te-rop'o-da (= Branchifera). 

Bran-chi-op'o-da (Gr. bragchia; and pous, foot). A legion of Crustacea, in 
which the gills are supported by the feet. 

Bran-chi-os'te-gal (Gr. bragchia, gills; stego, I cover). Applied to a mem¬ 
brane and rays by which the gills are protected in many fishes. 

Brev-i-lin'gui-a (Lat. brevis, snort; lingua, tongue). A division of the La- 
certilia. 

Brev-i-pen-na't^e (Lat. brevis, short; penna, a wing). A group of the Na¬ 
tatorial Birds. 

Bronch'i (Gr. brogchos , the windpipe). The branches of the windpipe 
(trachea), by which the air is conveyed to the vesicles of the lung. 

Bru'ta (Lat. brutus, heavy, stupid). Often used to designate the Mamma¬ 
lian order of the Edentata . 

Bry-o-zo'a (Gr. bruon , moss; zoon, animal). A synonym of Polyzoa , a class 
of the Molluscoida. 

Buc'oal (Lat. bucca, mouth or cheeks). Connected with the mouth. 

Bur'si-form (Lat. bursa, a purse; forma , shape). Shaped like a purse; sub- 
spherical. 

Bys-sif'e-rous. Producing a byssus. 

Bys'scs (Gr. bussos, flax). A term applied to the silky filaments by which 
the Pinna , the common Mussel, and certain other bivalve Mollusca , attach 
themselves to foreign objects. 

Ca-du-ci-branch'i-ate (Lat. caducns , falling off; Gr. bragchia , gills). Applied 
to those Amphibians in which the gills fall off before maturity is reached. 

Ca-du'cous. Applied to parts which fall off or are shed during the life of the 
animal. 

C^e'cal (Lat. coccus, blind). Terminating blindly, or in a closed extremity. 

C^e'cum (Lat. ccecm). A tube which terminates blindly. 

Cjss'pi-tose (Lat. ccespes , a turf). Tufted. 

Cai-no-zo'ic. (See Kainozoic.) 

Cal'car (Lat. for a spur). Applied to the “ spurs ” of Rasorial Birds; and 
also to the rudiments of the nind limbs in certain Snakes. 

Cal-ca're-ous (Lat. calx , lime). Composed of carbonate of lime. 

Cal'ice. The little cup in which the polype of a coralligenous Zoophyte 
( Actinozoon) is contained. 

Cal-y-co-phor'i-d^e (Gr. Icalux , a cup; and phero, I carry). An order of the 
oceanic Hydrozoa, so called from their possessing bell-shaped swimming 
organs ( nechocalyces ). 

Ca'lyx (Lat. calyx , a cup). Applied to the cup-shaped body of Vorticella 
(Protozoa), or of a Crinoid (Echinodermata). 

Cam-pan-u-lar'i-d^e (Lat. campanula, a little bell). An order of Hydroid Zoo¬ 
phytes. 

Ca-nine' (Lat. earns, a dog). The eye-tooth of Mammals, or the. tooth which 
is placed at or close to the praemaxillary suture in the upper jaw, and the 
corresponding tooth in the lower jaw. 

Ca-pit'u-lum (Lat. dim. of caput, head). Applied to the body of a Barnacle 
(Lepadidac), from its being supported upon a stalk or peduncle. 

Car'a-pace. A protective shield. Applied to the upper shells of Crabs, 
Lobsters, and many other Crustacea; also to the case with which certain 
of the Infusoria are provided. Also the upper half of the immovable case 
in which the body of a Chelonian is protected. 

Car-i-na'tjs (Lat. carina, a keel). Applied by Huxley to all those birds in 
which the sternum is furnished with a median ridge or keel. 

Car-niv'o-ra (Lat. caro, flesh; voro, I devour). An order of the Mammalia . 

Car-niv'o-rous (Lat. caro, flesh; voro, I devour). Reeding upon flesh. 

Car'nose (Lat. caro). Fleshy. . 

Car-poph'a-ga (Gr. karpos, fruit; phago, I eat). A section of the Marsvr 
pialia. , 


326 


GLOSSARY. 


Car'pus (Gr. karpos , the wrist). The small bones which intervene between 
the fore-arm and the metacarpus. 

Ca-tar'rhin-a (Gr. kata, downward; rhines , nostrils). A group of the 
Quadrumana. 

Cau'dal (Lat. cauda, the tail). Belonging to the tail. 

Cav-i-cor'ni-a (Lat. cavus, hollow; cornu, a horn). The “hollow-horned” 
Ruminants, in which the horn consists of a central bony “ horn-core ” sur¬ 
rounded by a homy sheath. 

Cen'trum (Gr. kerdron, the point round which a circle is described by a pair 
of compasses). The central portion or “ body ” of a vertebra. 

Ce-phal'ic (Gr. kephale, head). Belonging to the head. 

Ceph-a-lo-branch'i-ate (Gr. kephale ; aud bragchia, gills). Carrying gills upon 
the head. Applied to a section of the Annelida, which, like the Serpuloe , 
have tufts of external gills placed upon the head. 

Ceph-a-loph'o-ra (Gr. kephale ; axidphero, I carry). Used synonymously with 
Encephala, to designate those Mollusca which possess a distinct head. 

Ceph-a-lop'o-da (Gr. kephale ; and podes, feet). A class of the Mollusca ? com¬ 
prising the Cuttle-fishes and their allies, in which there is a series or arms 
ranged round the head. 

Ceph-a-lo-tho'rax (Gr. kephale; and thorax, chest). The anterior division 
of the body in many Crustacea and Arachnida, which is composed of the 
coalesced head and chest. 

Cere. The naked space found at the base of the bill of some birds. 

Cer'e-bral. 

Cer'e-bruh. 

Cer'vi-cal (Gr. cervix, neck). Connected with the region of the neck. 

Ces-toid'e-a (Gr. kestos, a girdle). An old name for the Tceniada, a class of 
intestinal worms with fiat bodies like tape (hence the name Tapeworms). 

Ces-traph'o-ri (Gr. kestra, a weapon; phero, I carry). The group of Elasmo - 
branchii represented at the present day by the Port Jackson Shark. 

Ce-ta'ce-a (Gr. ketos, a whale). The order of Mammals comprising the 
Whales and Dolphins. 

Cile-tog'na-tha (Gr. chaite, bristle; gnoihos,]scw). An order of the Anar - 
thropoda, comprising only the oceanic genus Sagitta. 

Chei-rop'ter-a (Gr. cheir, ‘hand; pteron , a wing). The order of Mammals 
comprising the Bats. 

CHE'Ln (Gr. chele, a claw). The prehensile claws with which some of the 
limbs are terminated in certain Crustacea, such as the Crab, Lobster, etc. 

Che'late. Possessing chela?; applied to a limb. 

Che-lio'e-r^e (Gr. chele, a claw; and keras, a hom). The prehensile claws 
of the Scorpion, supposed to be homologous with antenna?. 

Ciie-lo'ni-a (Gr. chelone, a tortoise). The order of Reptiles comprising the 
Tortoises and Turtles. 

Che-lo-no-ba-tra'chi-a (Gr. chelone, a tortoise; batrachos, a frog). Some¬ 
times applied to the Amphibian order of the Anoura (Frogs and Toads). 

Chi-log'na-tha (Gr. cheilos, a lip; and gnathos , a jaw). An order of the My~ 
riapoda. 

Chi-lop'o-da (Gr. cheilos; antipodes, feet). An order of the Myriapoda. 

Chi'tine (Gr. chiton, a coat). The peculiar chemical principle, nearly allied 
to horn, which forms the exoskeleton in many Invertebrate animals, espe¬ 
cially in the Arthropoda ( Crustacea, Insecta, etc.). 

Chlo'ro-phyll (Gr. chloros, green; and phullon, a leaf). The green coloring 
matter of plants. 

Chro-mat'o-phores (Gr. chroma, complexion, or color; and phero, I carry). 
Little sacs which contain pigment-granules, and are found in the integu¬ 
ment of Cuttle-fishes. 

Chrys'a-lis (Gr. chrusos, gold)^ The motionless pupa of butterflies and 
moths, so called because sometimes exhibiting a golden lustre. 

Chy-la'que-ous fluid. A fluid consisting partly of water derived from the 
exterior, and partly of the products of digestion (chyle), occupying the 
body-cavity or perivisceral space in many Invertebrates ( Annelides, Echino • 


GLOSSARY. 327 

denns , etc.), and sometimes having a special canal-system for its conduction 
(chylaqueous canals). 

Chyle (Gr. chulos , juice). The milky fluid which is the result of the action 
of the various digestive fluids upon the food. 

Chy-lif'ic (Gr. chulos, juice [chyle]; and Lat. facio, I make). Producing 
chyle. Applied to one of the stomachs, when more than one is present. 
The word is of mongrel origin; and “chylopoetic” is more correct. 

Chyme (Gr. chumos, juice). The acid, pasty fluid produced by the action of 
the gastric juice upon the food. 

Chyme-mass. The central, semi-fluid sarcode in the interior of an Infusorian. 

Cil'i-a (Lat. cilium , an eyelash). Microscopic, hair-like filaments, which 
have tne power of lashing backward and forward, thus creating currents in 
the surrounding or contiguous fluid, or subserving locomotion in the animal 
which possesses them. 

Cil-i-o-gra'da (Lat. cilium; and gradior , I walk). Synonymous with Cteno- 
phora , an order of Actinozoa. 

Cin'oli-des (Gr. kigklis , a lattice). Special apertures in the column-walls of 
some Sea-anemones ( Actinia: ), whicn probably serve for the emission of 
the cord-like “ craspeda.” 

Cir'ri (Lat. cirrus, a curl). Tendril-like appendages, such as the feet of 
Barnacles and Acom-shells ( Cirripedes), the lateral processes on the arms 
of Brachiopoda, etc. 

Cir-rif'er-ous or Cir-rig'er-ous. Carrying cirri. 

Cir-ri-pe'dia, Cir-rhi-pe'di-a, or Cir-rhop p o-da (Lat. cirrus, a curl; and pes, a 
foot). A sub-class of Crustacea with curled jointed feet. 

Cir-ros'to-mi (Lat. cirrus, a tendril; Gr. stoma , mouth). Sometimes used to 
designate the Bharyngobranchii. 

Cla-doc'e-ra (Gr. klados , a branch; fceras, a horn). An order of Crustacea 
with branched antennae. 

Cla'vate (Lat. clavus } a club). Club-shaped. 

Clav'i-cle (Lat. clavicula, a little key). The “ collar-bone,” forming one of 
the elements of the pectoral arch of Vertebrates. 

Clo-a'ca (Lat. for a sink). The cavity into which the intestinal canal and 
the ducts of the generative and urinary organs open in common, in some 
Invertebrates ( e. g., in Insects), and also in many Vertebrate animals. 

Clyp'e-i-form (Lat. clypeus. a shield; and forma, shape). Shield-shaped ; 
applied, for example, to the carapace of tne King-crab. 

Cni'd^e (Gr. Tcnide, a nettle). The urticating cells, or “thread-cells,” where¬ 
by many Coelenterate animals obtain their power of stinging. 

Coo'co-liths (Gr. kokkos, a berry; lithos, stone). Minute oval or rounded 
bodies, which are found either free or attached to the surface of cocco- 
spheres. 

Coo'co-spheres (Gr. kokkos ; and sphaira, a sphere). Spherical masses of sar¬ 
code, enclosed in a delicate calcareous envelope, and bearing coccoliths 
upon their external surface. Both coccospheres and coccoliths are em¬ 
bedded in a diffused plasmodium of sarcode, the whole constituting a low 
Rhizopodic organism. 

Coc-cyg'e-al. Connected with the coccyx. 

Coc'cyx (Gr. kokkux, a cuckoo). The terminal portion of the spinal column 
in man, so called from its resemblance to a cuckoo’s beak. 

Co-coon' (French cocon, the cocoon of the silk-worm; connected with Fr. 
cogue , shell, which is derived from the Lat. concha). The outer covering 
01 silky hairs with which the pupa or chrysalis of many insects is protected. 

Co-do-nos'to-ma (Gr. kodon, a bell; stoma, mouth). Tne aperture or mouth 
of the disc (nechocalyx) of a Medusa, or of the bell (gonocalyx) of a raedusi- 
form gonophore. 

C<e-len-te-ra'ta (Gr. koilos, hollow; enieron, the bowel). The sub-kingdom 
which comprises the Hydrozoa and Actinozoa. Proposed by Frey and 
Leuckhart in place of the old term Radiata, which included other animals 
as well. 

C(E-nen'chy-ma (Gr. koinos, common; egchuma, tissue). The common cal- 


328 


GLOSSARY. 


care on s tissue which unites together the various corallites of a compound 
coralluin. 

Cce-n<e'ci-um (Gr. Jcoinos , common; oikos, house'). The entire dermal system 
of any Polyzo n ; employed in place of the terms polyzoary or polypidom. 

Ccen'o-sarc (Gr. hoinos, common; sane, flesh). The common organized me¬ 
dium by which the separate polypites of a compound Hydrozoon are con¬ 
nected together. 

Col-e-op'ter-a (Gr. Icoleos a sheath; pteron , wing). The order of Insects 
(Beetles) in which the anterior pair of wings are hardened, and serve as 
protective cases for the posterior pair of membranous wings. 

Col-u-bri'na (Lat. coluber , a snake). A division of the Ophidia. 

Col-tjm-ba'ce-i (Lat. columba , a dove). The division of Kasorial Birds com¬ 
prising the Doves and Pigeons. 

Col-u-mel'la (Lat. dim. of columna , a column). In Conchology, the central 
axis round which the whorls of a spiral univalve are wound. Amongst the 
Actinozoa , it is the central axis or pillar which is found in the centre of the 
thecae of many corals. 

Col'umn. Applied to the cylindrical body of a Sea-anemone ( Actinia ) / also 
to the jointed stem or peduncle of the stalked Crinoids. 

Com-mis'su-ral (Lat. committo, I solder together). Connecting together ; 
usually applied to the nerve-fibres which unite different ganglia. 

Con'cha (Lat. for a shell). The external ear by which sounds are collected 
and transmitted to the internal ear. 

Con-chif'e-ra (Lat. concha , a shell; fero, I carry). Shell-fish. Applied in a 
restricted sense to the bivalve Molluscs, and used as a synonym for Lamelli- 
branchiata. 

Con'd yle (Gr. hondulos , a knuckle). The surface by which one bone articu¬ 
lates with another. Applied especially to the articular surface or sur¬ 
faces by which the skull articulates with the vertebral column. 

Con-i-ros'tres ( Lat. conus, a cone; rostrum , a beak). The division of Perch¬ 
ing Birds with conical beaks. 

Co pep'o-da (Gr. hope, an oar; podes, feet). An order of Crustacea. 

Cor'a-coid (Gr. horax , a crow; eidos, form). One of the bones which enters 
into the composition of the pectoral arch in Birds, Reptiles, and Mono- 
tremes. In most Mammals it is a mere process of the scapula, having, in 
man, some resemblance in shape to the beak of a crow. 

Cor-al-lig'en-ous. Producing a corallum. 

Cor'al-lite. The corallum secreted by an Actinozoon which consists of a 
single polype; or the portion of a composite corallura which belongs to, 
ana is secreted by, an individual polype. 

Cor-al'lum (from the Latin for red coral). The hard structures deposited in, 
or by ? the tissues of an Actinozoon —commonly called a “ coral.” 

Co-ri-a ceous (Lat. corium , hide). Leathery. 

Cor'pus Cal-lo'sum (Lat. for the “ firm body ”). The great band of nervous 
matter which unites the two hemispheres of the cerebrum in the Mammals. 

Cor-pus'ou-la-ted (Lat. corpusculum , a little body or particle). Applied to 
fluids which, like the blood, contain floating solid particles or “ corpuscles.” 

Cor'ti-cal lay'er. The layer of consistent sarcode, which in the Inf usoria 
encloses the chyme mass, and is surrounded by the cuticle. Sometimes 
called the “ parenchyma of the body.” 

Co-ryn'i-da. 

Cos'tjE (Lat. costa , a rib). Applied amongst the Crinoidea to designate the 
rows of plates which succeed the inferior or basal portion of the cup (pel¬ 
vis). Among the Corals the “costae” are vertical ridges which occur on the 
outer surface of the theca, and mark the position of the septa within. 

Cos'tal (Lat. costa , a rib). Connected with the ribs. 

Cra'ni-tjm (Gr. hr anion, the skull). The bony or cartilaginous case in which 
the brain is contained. 

Cras'pe-da (Gr. kraspedon , a margin or fringe). The long, convoluted cords, 
containing thread-cells, which are attached to the free margins of the 
mesenteries of a Sea-anemone. 


GLOSSARY. 


329 


Cre-pus'cit-lar (Lat. crepusculum, dusk). Applied to animals which are 
active in the dusk or twilight. 

Cri-noi'de-a (Gr. krinon, a lily; eidos, form). An order of Echinodermata, 
comprising forms which are usually stalked, and sometimes resemble lilies 
in shape. 

Croc-o-dil'ia (Gr. krokodeilos, a crocodile). An order of Reptiles. 

Crop. A.partial dilatation of the gullet, technically called “ ingluvies.” 

Crus-ta'ce-a (Lat. crusta, a crust). A class of articulate animals, comprising 
Crabs, Lobsters, etc., characterized by the possession of a hard shell or 
crust, which they cast periodically. 

Cten'o-cyst (Gr. kteis, a comb; kustis, a bag or cyst). The sense-organ (prob¬ 
ably auditory) which occurs in the Ctenophora. 

Cte'noid (Gr. kteis, a comb; eidos, form). Applied to those scales of fishes, 
the hinder margins of which are fringed with spines or comb-like pro¬ 
jections. , 

Cte-nopii'o-ra (Gr. kteis, a comb; and phero, I carry). An order of Actinozoa , 
comprising oceanic creatures, which swim by means of “ ctenophores,” or 
banas of cilia arranged in comb-like plates. 

Cur-so'res (Lat. curro, I run). An order of Aves, comprising birds destitute 
of the power of flight, but formed for running vigorously (e. g., the Ostrich 
and Emeu). 

Cus'pi-date. Furnished with small pointed eminences or “ cusps.” 

Cu'ti-cle (Lat. cuticula, dim. of cutis, skin). The pellicle which forms the 
outer layer of the body among the Infusoria. The outer layer of the in¬ 
tegument generally. 

Cu'tis (Lat. for skin). The inferior vascular layer of the integument, often 
called the cutis vera, the corium, or the derma. 

Cy'cloid (Gr. kuklos. a circle; eidos, form). Applied to those scales of fishes 
which have a regularly circular or elliptical outline with an even margin. 

Cy-clos'to-mi. Sometimes used to designate the Hag-fishes and Lampreys, 
forming the order Marsipobranchii. 

Cyst (Gr. kustis , a bladder or bag). A sac or vesicle. 

Cys'tic. 

Cys'ti-ca. The embryonic forms (scolices)of certain intestinal worms (Tape¬ 
worms), which were described as a distinct order, until their true nature 
was discovered. 

Cys-toi'de-a (Gr. kustis, a bladder; and eidos, form). An extinct order of 
Echinodermata. 


a (Gr. deka, ten; podes, feet). The division of Crustacea which 
ambulatory feet; also the family of Cuttle-fishes, in which there 


De-cap'o-da 
have ten 

are ten arms or cephalic processes. 

De-cid'u-ous (Lat. decido, 1 fallpff). Applied to parts which fall off or are 
shed during the life of the animal. 

De-col'la-ted (Lat. decollo, I behead). Applied to univalve shells, the apex 


of which falls off’ in the course of growth. 
>ei-no-sau'ri-a (Gr. deinos , terrible; saura, lizard). 


Dei-no-sau'ri-a (Gr. deinos. terrible: saura , lizard). An extinct order of 
Reptiles. 

Den'dri-form, Den-drit'ic, Dendroid (Gr. dendron , a tree). Branched like 
a tree, arborescent. 

Den'tal. 

Den-ti-ros'tres (Lat. dens , a tooth; rostrum, a beak). The group of Perching 
Birds in which the upper mandible of the beak has its lower margin toothed. 

Der'ma. (See Cutis.) 

Der'mal (Gr. derma, skin). Belonging to the integument. 

Der-mo-scle'rites (Gr. derma, skin; skleros, hard). Masses of spicules which 
occur in the tissues of some of the Alcyonidce (Actinozoa). _ 

Des-mid'i-.<e. Minute fresh-water pi mts, of a green color, without a siliceous 
epidermis. , 

Deit-ter-o-zo'oids (Gr. deuteros, second; zoin, animal; eidos, form). I he 
zo. ids which are produced by gemmation from zooids. 


330 


GLOSSARY. 


Dex'tral (Lat. dextra, the right hand). Right-handed; applied to the direc¬ 
tion of the spiral in the greater number of univalve shells. 

Di'a-phragm (Gr. diaphragma , a partition). The “ midriff,” or the muscle 
which in Mammalia forms a partition between the cavities of the thorax 
and abdomen. 

Di-a-ste'aia (Gr. dia, apart; histemi , to place). A gap or interval, especially 
between teeth. 

Di-as'to-le (Gr. diastello , I separate or expand). The expansion of a contrac¬ 
tile cavity such as the heart, which follows its contraction or “systole.”. 

Di-a-to-ma'ce-^e (Gr. diatemno , I sever). An order of minute plants, which 
are provided with siliceous envelopes. 

Di-branch-i-a'ta (Gr. dis, twice; bragchia, gills). The order of Cephalopoda 
(comprising the Cuttle-fishes, etc.), in which only two gills are present. 

Di-cyn-o-don'ti-a (Gr. dis, twice; kuon , dog; odous , tooth). An extinct order 
of Reptiles. 

Di-del'phi-a (Gr. dis, twice; delphus , womb). The subdivision of Mammals 
comprising the Marsupials. 

Dig'it (Lat. digitus , a finger). A finger or toe. 

Dig-i-ti-gra'da (Lat. digitus / gradior , I walk). A subdivision of the Car¬ 
nivora. 

Dig'i-ti-grade. Walking upon the tips of the toes, and not upon the soles 
of the feet. 

Dim-e-ro-so'ma-ta (Gr. disjmeros , part; soma, body). An order of Arachnida, 
comprising the true Spiders, so called from the marked division of the body 
into two regions, the cephalothorax and abdomen. The name Araneida is 
often employed for the order. 

Dimt-a-rt (Gr. dis , twice; mus, muscle). Applied to those bivalve Molluscs 
(. Lamellibranchiata) in which the shell is closed by two adductor muscles. 

Di-ce'cious (Gr. dis , twice; oikos, house). Having the sexes distinct; applied 
to species which consist of male and female individuals. 

Diph'y-o-dont (Gr. dis, twice; phuo, I generate; odous, tooth). Applied to 
those Mammals which have two sets of teeth. 

Diph-y-o-zo'oids. Detached reproductive portions of adult Calycophoridce, an 
order of oceanic Hydrozoa. 

Dipnoi (Gr. dis , twice; pnoe, breath). The order of Fishes represented by 
the Lepidosiren. 

Dip'ter-a (Gr. dis , twice; pteron , wing). An order of Insects characterized 
by the possession of two wings. 

Diso'oid (Gr. diskos , a quoit; eidos, form). Shaped like a round plate or quoit. 

Dis-coph'o-ra (Gr. diskos^ a quoit; phero , I carry). This term is applied to 
the Medusae , or Jelly-nshes, from their form; and is sometimes used to 
designate the order of the Leeches ( Hirudinea ), from the suctorial discs 
which these animals possess. 

Dis-sep'i-ments (Lat. dissepio , I partition off). Partitions. Used in a restricted 
sense to designate certain imperfect transverse partitions, which grow from 
the septa of many corals. 

Dis'tal. Applied to the quickly-growing end of the hydrosoma of a Hydro- 
zo'in; the opposite, or “proximal,” extremity growing less rapidly, and 
being the end by which the organism is fixed, when attached at all. 

Di-ur'nal (Lat. dies, day). Applied to animals which are active during the 
day. 

Di-ver-tio'u-lum (Lat. diverticulum, a by-road). A lateral tube with a blind 
extremity springing from the side of another tube. 

Dor'sal (Lat. dorsum, back). Connected with the back. 

Dor-si-branch'i-ate (Lat. dorsum , the back; Gr. bragchia , gills). Having ex¬ 
ternal gills attached to the back; applied to certain Annelides and Molluscs. 
The term is of mongrel composition, and “ notobranchiate ” is more cor¬ 
rectly employed. 

Eo'de-ron (Gr. ek, out; deros, skinb The outer plane of growth of the ex¬ 
ternal integumentary layer (viz., tne ectoderm, or epidermis). 


GLOSSARY. 


331 


Ec'dy-sis (Gr. ekdusis , a stripping off). A shedding or moulting of the skin. 

E-chi-no-coc'ci (Gr. echinos , a hedgehog; kokkos , a berry). The larval forms 
(scolices) of the tapeworm of the dog {Taenia echinococcus), commonly 
known as “hydatids.” 

E-chi-no-der'ma-ta (Gr. echinos ; and derma , skin). A class of animals com¬ 
prising the Sea-urchins, Star-fishes, and others, most of which have spiny 
skins. 

E-chi-noi'de-a (Gr. echinos ; and eidos, form). An order of Echinodermata , 
comprising the Sea-urchins. 

E-chin'u-late. Possessing spines. 

Eo'to-cyst (Gr. ektos, outside ; kustis, a bladder). The external investment 
of the coenoecium of a Polyzoon. 

Ec'to-derm (Gr. ektos ; and derma, skin). The external integumentary layer 
of the Coelenterata. 

Eo'to-saro (Gr. ektos; sarx , flesh). The outer transparent sarcode-layer of 
certain Rhizopods, such as the Amoeba. 

E-den-ta'ta (Lat. e, without; dens, tooth). An order of Mammalia often 
called Bruta. 

E-den'tu-lous. Toothless; without any dental apparatus. Applied to the 
mouth of any animal, or to the hinge of the bivalve Molluscs. 

E-dri-oph-thal'ma-ta (Gr. hedraios, sitting; ophthalmos, eye). The division of 
Crustacea in which the eyes are sessile, and are not supported upon 
stalks. 

E-las-mo-branch'i-i (Gr. elasma, a plate; bragchia , gills). An order of 
Fishes, including the Sharks and Rays. 

El'y-tra (Gr. elutron, a sheath). The chitinous anterior pair of wings in 
Beetles, which form cases for the posterior membranous wings. Also ap¬ 
plied to the scales or plates on the Dack of the Sea-mouse {Aphrodite). 

Em'bry-o (Gr. en, in: bruo, I swell). The earliest stage at which the young 
animal is recognizable in the impregnated ovum. 

En-ceph'a-lon (Gr. egkephalos, brain). . The portion of the cerebro-spinal 
nervous axis contained within the cranium. 

En-ceph'a-lous (Gr. en, in; kephale, the head). Possessing a distinct head. 
Usually applied to all the Mollusca proper, except the Lamellibranchiata. 

En-cys-ta'tion (Gr. en, in; kustis, a bag). The transformation undergone by 
certain of the Protozoa , when they become motionless, and surround them¬ 
selves by a thick coating or cyst. 

En'de-ron (Gr. en, in; deros, skin). The inner plane of growth of the outer 
integumentary layer (viz., the ectoderm, or epidermis). 

En'do-cyst (Gr. endon. within; kustis, a bag). The inner membrane or in¬ 
tegumentary layer or a Polyzoon. In Cristatella, where there is no “ ecto- 
cyst,” the endocyst constitutes the entire integument. 

En do-derm (Gr. endon ; and derma, skin). The inner integumentary layer 
of the Coelenterata. 

En-dop'o-dite (Gr. endon; and pous, foot). The inner of the two secondary 
joints into which the typical limb of a Crustacean is divided. 

En'do-sarc (Gr. endon ; and sarx, flesh). The inner molecular layer of sarcode 
in the Amoeba and other allied Rhizopods. 

En-do-skel'e-ton (Gr. endon; and skeletos, dry). The internal hard struc¬ 
tures, such as bones, which serve for the attachment of muscles, or the pro¬ 
tection of organs, and which are not a mere hardening of the integument. 

En'si-form (Lat. ensis, a sword; forma, shape). Sword-shaped. 

En-to-moph'a-ga (Gr. entoma , insects; phago, I eat). A section of the Mar- 
supialia. 

En-to-mos'tra-ka (Gr. entoma, insects; ostrakon, a shell). Literally, shelled 
insects—applied to a division of Crustacea. 

En-to-zo'a (Gr. entos, within; zobn, animal). Animals which are parasitic in 
the interior of other animals. 

E'o-cene (Gr. eos, dawn; kainos, new or recent). The lowest division of the 
Tertiary rocks, in which species of existing shells are to a small extent 
represented. 


332 


GLOSSARY. 


Ep-i-der'mis (Gr. epi, upon ; derma , the true skin). _ The outer non-vascular 
layer of the skin, often called the scarf-skin or cuticle. 

Ep-i-me'ra (Gr. epi , upon; meron , thigh). The lateral pieces of the dorsal 
arc of the somite of a Crustacean. 

Ep-i-po'di-a (Gr. epi , upon; pous , the foot). Muscular lohes developed from 
the lateral and upper surfaces of the “foot” of some Molluscs. 

E-pxp'o-dite (Gr. epi , upon; pous , foot). A process developed upon the basal 
joint, or “ protopodite,” of some of the limbs of certain Crustacea. 

Ep-i-ster'na (Gr. epi , upon; sternon , the breast-bone). The lateral pieces 
of the inferior or ventral arc of the somite of a Crustacean. 

Ep'i-stome (Gr. epi; and stoma , mouth). A valve-like organ which arches 
over the mouth in certain of the Polyzoa. 

Ep-i-the'ca (Gr. epi; and theke, a sheath). A continuous layer surrounding 
the thecae in some Corals, and being the external indications of tabulae. 

Ep-i-zo'a (Gr. epi, upon; zoon, animal). Animals which are parasitic upon 
other animals. In a restricted sense, a division of Crustacea which are 
parasitic upon fishes. 

E-qui-lat'er-al (Lat. cequus , equal; latus, side). Having its sides equal. 
Usually applied to the shells of the Bradiiopoda. When applied to the 
spiral shells of the Foraminifera, it means that all the convolutions of the 
shell lie in the same plane. 

E'qui-valve (Lat. cequus , equal; valvce, folding-doors). Applied to shells 
which are composed of two equal pieces or valves. 

Er-ran'ti-a (Lat. erro, I wander). An order of Annelida , often called Nereidea , 
distinguished by their great locomotive powers. 

Eu-ryp-ter'i-da (Gr. eurus , broad; pteron , wing). An extinct sub-order of 
Crustacea. 

Ex-op'o-dite (Gr. exo, outside; pous, foot). The outer of the two secondary 
joints into which the typical limb of a Crustacean is divided. 

Ex-o-skel'e-ton (Gr. exo , outside; skeletos , dry). The external skeleton, 
which is constituted by a hardening of the integument, and is often called 
a “ dermoskeleton.” 

Fas-cic'u-la-ted (Lat. fasciculus, a bundle). Arranged in bundles. 

Fau'na (Lat. Fauni , the rural deities of the Romans). The general assem¬ 
blage of the animals of any region or district. 

Fe'mur. The thigh-bone, intervening between the pelvis and the bones of 
the leg proper (tibia and Jibula). 

Fib'u-la (Lat. a brooch). The outermost of the two bones of the leg in the 
higher Vertebrata ; corresponding to the ulna of the fore-arm. 

Fil'i-form (Ldt.Jilum, a thread; forma } shape). Thread-shaped. 

Fis-si-ljn'gui-a (Lat. Jindo, I cleave; lingua , tongue). A division of Lacer- 
tilia , with bifid tongues. 

Fis'siox (Lat. Jindo , I cleave). Multiplication by means of a process of self¬ 
division. 

Fis-sip'a-rous (Lat. Jindo; and pario , I produce). Giving origin to fresh 
structures by a process of fission. 

Fis-si-ros'tres (Lat. Jindo, I cleave; rostrum , beak). A sub-order of the 
Perching Birds. 

Fla-gel'lum (Lat. for whip). The lash-like appendage exhibited by many 
Infusoria , which are therefore said to be “ flagellate.’’ 

Flo'ra (Lat. Flora } the goddess of flowers). The general assemblage of the 
plants of any region or district. 

Foot. 

Foot-jaws. The limbs of Crustacea, which are modified to subserve mastica¬ 
tion. 

Foot-se-cre'tioh-. The term applied by Mr. Dana to the sclerobasic corallum 
of certain Actinozoa. 

Foot-tu'ber-cles. The unarticulated appendages of th6 Annelida , often 
called parapodia. 

Fo-ram-i-nif e-ra (Lat. foramen , an aperture; fero, I carry). An order of 


GLOSSARY. 


333 


Protozoa, usually characterized by the possession of a shell perforated by 
numerous pseudopodial apertures. 

Fru-giv'o-rous (Lat. frux , fruit; voro , I devour). Living upon fruits. 

Fun'nel. 

Fur'ou-lum (Lat. dim. of furca , a fork). The “ merry-thought” of birds, or 
the V-shaped bone formed by the united clavicles. 

Fu'si-form (Lat. fusus , a spindle; and forma , chape). Spindle-shaped, or 
pointed at both ends. 


Gal-li-na'ce-i (Lat. gallina , a fowl). Sometimes applied to the whole order 
of the Rasorial Birds, but properly restricted to that section of the order 
of which the common Fowl is a typical example. 

Gan'gli-on (Gr. gagglion , a knot). A mass of nervous matter containing 
nerve-cells, giving origin to nerve-fibres. 

Ga'noid (Gr. ganosy splendo^ brightness). Applied to those scales or plates 
which are composed of an inferior layer of true bone covered by a superior 
layer of polished enamel. 

Ga-noi'de-a. An order of Fishes. 

Gas-te-rop'o-da (Gr. gaster, stomach ; pous , foot). The class of the Mollusca 
comprising the ordinary univalves, in which locomotion is usually effected 
by a muscular expansion of the under surface of the body (the “ root”). 

Gem'm.e (Lat. gemma , a bud). The buds produced by any animal, whether 
detached or not. 

Gem-ma'tion. The process of producing new structures by budding. 

Geii-mip'ar-ous (Lat. gemma , a bud; pario , I produce). Giving origin to new 
structures by a process of budding. 

Gem'mules (Lat. dim. of gemma). The ciliated embryos of many Coelenterata ; 
also the seed-like reproductive bodies or “ spores” of Spongilla. 

Ge-phyr'e-a (Gr. gephura , a bridge). A class of the Anarthropoda , com¬ 
prising the Spoon-worms ( Sipunculus ) and their allies. 

Giz'zard. A muscular division of the stomach in Birds, Insects, etc. 

Gla'di-us (Lat. for a sword). Applied to the horny endoskeleton or “pen” 
of certain Cuttle-fishes. 

Glenoid (Gr. glene , a cavity; eidos, form). A shallow cavity; applied espe¬ 
cially to the shallow articular cavity in the shoulder-blade to which the 
heaa of the humerus is jointed. 

Gnath'ites (Gr. gnathos , a jaw). The masticatory organs of Crustacea. 

Gon-o-blas-tid'i-a (Gr. gonos . offspring; blastidion , dim. of blastos, a bud). 
The processes which carry tne reproductive receptacles, or “ gonophores,” 
in many of the Hydrozoa. 

Gon-o-ca'lyx (Gr. gonos; and Jcalux, cup). The swimming-bell in a medusi- 
form gonophore, or the same structure in a gonophore which is not detached. 

Gon'o-phore (Gr. gonos; and phero, I carry). The generative buds, or recep¬ 
tacles of the reproductive elements, in the Hydrozoa , whether these become 
detached or not. 

Gon'o-some (Gr. gonos; and soma , body). Applied as a collective term to 
the reproductive zooids of a Hyarozoon. 

Gon-o-the'ca (Gr. gonos ; and theke, a case). The chitinous receptacle within 
which the gonophores of certain of the Hydrozoa are produced. 

Gral-la-to'res (Lat. grallce , stilts). The order of the long-legged Wading- 


Birds. 

Gra-niv'o-rous (Lat. granum , a grain or seed; voro ,I devour). Living upon 
grains or other seeds. 

Grap-to-lit'1-d.e (Gr. grapho , I write; lithos, stone). An extinct sub-class 
of the Hydrozoa. 

Greg-a-rin'i-da (Lat. gr eg arms, occurring in numbers together). A class of 
the Protozoa. , 

Guard. The cylindrical fibrous sheath with which the internal chambered 
shell (phragmacone) of a Belemnite is protected. 

Gul'let. 

Gym-no-las'ma-ta (Gr. gumnos, naked ; laimos , the throat). An order of the 


334 


GLOSSARY. 


Polyzoa in which the mouth is devoid of the valvular structure known as 
the “ epistome.” # 

Gym-no-phi'o-na (Gr. gumnos , naked; ophis , a snake). The order of the 
Amphibia comprising the snake-like CcBcili/B. 

Gym-noph-thal'ma-ta (Gr. gumnos / and ophthalmos , the eye). Applied by 
Edward Forbes to those Medusae in which the eye-specks at the margin of 
the disc are unprotected. The division is now abandoned. 

Gym-no-so'ma-ta (Gr. gumnos ; and some ; , the body). The order of Pteropoda 
in which the body is not protected by a shell. 

Gyn'o-phores (Gr. gune, woman; phero, I carry). The generative buds, or 
gonophores, of Hydrozoa , which contain ova alone, and differ in form from 
those which contain spermatozoa. 

Gy-ren-ceph'a-la (Gr. guroo , I wind about; eglcephalos , brain). Applied by 
Owen to a section of the Mammalia in which the cerebral hemispheres are 
abundantly convoluted. 

ILe'mal (Gr. haima, blood). Connected with the blood-vessels, or with the 
circulatory system. 

H^e-ma-toc ry-a (Gr. haima , blood; Jcruos , cold). Applied by Owen to the 
“cold-blooded” Vertebrates—viz., the Fishes, Amphibia, and Reptiles. 

H^-ma-to-ther'ma (Gr. haima , blood; thermos , warm). Applied by Owen to 
the “warm-blooded” Vertebrates—viz., Birds and Mammals. 

Hal'lux (Lat. allex , the thumb or great toe). The innermost of the five 
digits which normally compose the hind foot of a Vertebrate animal. In 
man, the great toe. 

Hal-te'res (Gr. halt'^res , weights used by athletes to steady themselves in 
leaping). The rudimentary filaments or “balancers” which represent the 
posterior pair of wings in the Diptera , an order of Insects. 

IIaus'tel-late (Lat. haurio , I drink). Adapted for sucking or pumping up 
fluids ; applied to the mouth of certain Crustacea and Insecta. 

Hec-to-cot y-lus (Gr. hekaton, a hundred ; Tcotulos , a cup). The metamor¬ 
phosed reproductive arm of certain of the male Cuttle-fishes. In the 
Argonaut the arm becomes detached, and was originally described as a 
parasitic worm. 

Hel'min-thoid (Gr. helmins , an intestinal worm). Worm-shaped, vermiform. 

He-mel'y-tra (Gr. hemi, half; elutron , a sheath). The wings of certain In¬ 
sects, in which the apex of the wing is membranous, while the inner por¬ 
tion is chitinous, and resembles the elytron of a beetle. 

Hem-i-met-a-bol'ic (Gr. hemi, half; metabole , change). Applied to those 
insects which undergo an incomplete metamorphosis. 

He-mip'te-ra (Gr. hemi; and pteron , wing). An order of insects in which 
the anterior wings are sometimes “ hemelytra.” 

Her-maph'ro-dite (Gr. Hermes , Mercury; Aphrodite , Venus). Possessing 
the characters of both sexes combined. 

Het-e-ro-cer'cal (Gr. heteros , diverse; kerlcos, tail). Applied to the tail of 
Fishes when it is unsymmetrical, or composed of two unequal lobes. 

Het-e-ro-ge'ne-ous. 

Het-e-ro-gan'gli-ate (Gr. heteros , diverse; gagglion, a knot). Possessing a 
nervous system in which the ganglia are scattered and unsymmetrical (as 
in the Mollusca, for example). 

Het-e-ro-mor'phic (Gr. heteros; morphe, form). Differing in form or shape. 

Het-e-roph'a-gi (Gr. heteros , other: phago , I eat). Applied to Birds the 
young of which are bom in a helpless condition, and require to be fed by 
the parents for a longer or shorter period. 

Het-e-rop'o da. 

IIex'a-pod (Gr. hexa, six; pous, foot). Possessing six legs; applied to the 
Insecta. 

IIi'lum (Lat. hilum , a little thing). A small aperture (as in the gemmules of 
sponges), or a small depression (as in Noctiluca). 

Hir-u-din'e-a (Lat. hirudo , a horse-leech). The order of Annelida com¬ 
prising the Leeches. 


GLOSSARY. 


335 


His-tol'o-oy (Gr. histos, a web; logos, a discourse). The study of the tissues, 
more especially of the minuter elements of the body. 

IIol-o-ceph'a-li (Gr. holos, whole; kephale , head). A sub-order of the 
Masmobranchii, comprising the Chimcerce. 

IIol-o-met-a-bol'ic (Gr. holos , whole; metabole , change). Applied to insects 
which undergo a complete metamorphosis. 

IIol-o-sto'ma-ta (Gr. holos, whole; stoma, mouth). A division of Oasteropo- 
dous Molluscs, in which the aperture of the shell is rounded, or “entire.” 

IIol-o-thu-roi'de-a (Gr. holos; thura, door; and eidos , form). An order of 
.Echinodermata comprising the Trepangs. 

Hom-o-cer'cal (Gr. homos, same; kerkos . tail). Applied to the tail of Fishes 
when it is symmetrical, or composed or two equal lobes. 

Ho-mo-ge'ne-ous. 

Ho-mo-gan'gli-ate (Gr. homos, same; gagglion , a knot). Having a nervous 
system in which tne ganglia are symmetrically arranged (as in the Annu- 
losa, for example). 

Ho-mol'o-gous (Gr. homos ; and logos, a discourse). Applied to parts which 
are constructed upon the same fundamental plan. 

Ho-mo-mor'phous (Gr. homos ; and morphe, form). Having a similar external 
appearance or form. 

Hu'me-rus. The bone of the upper arm ( brachium ) in the Vertebrates. 

Hy'a-line (Gr. hualos, crystal). Crystalline or glassy. 

Hyd'-a-tids (Gr. hudatis, a vesicle). The vesicle containing the larval forms 
(.Echinococci ) of the tapeworm of the dog. 

Hy'dra-form. Resembling the common fresh-water polype {Hydra) in form. 

Hy'dra. 

Hy-dro-cau'lus (Gr. hudra, a water-serpent; and kaulos, a stem). The main 
stem of the coenosarc of a Hydrozobn. 

IIy'-dro-cysts (Gr. hudra ; and Tcustis, a cyst). Curious processes attached to 
the coenosarc of the Physophoridoz, and termed “ feelers ” {Fuhler and Taster 
of the Germans). 

IIy-drie'ci-um (Gr. hudra; and oikos, a house). The chamber into which the 
coenosarc in many of the Calycophoridce can be retracted. 

Hy-droi'da (Gr. hudra ; and eidos, form). The sub-class of the Hydrozoa, 
which comprises the animals most nearly allied to the Hydra. 

Hy-dro-phyl'li-a (Gr. hudra; and phullon, a leaf). Overlapping append¬ 
ages or plates which protect the polypites in some of the oceanic Hydrozoa 
{Calycophoridce and Physophoridoz). They are often termed “ bracts,” and 
are the Deckstucke of the Germans. 

Hy-dro-rhi'za (Gr. hudra; and rhiza, root). The adherent base or proximal 
extremity of any Hydrozobn. 

Hy-dro-so'ma (Gr. hudra ; and soma, body). The entire organism of any 
Hydrozobn. 

Hy-dro-the'ca (Gr. hudra • and theke, a case). The little chitinous cups in 
which the polypites of the Sertularida and Campanularida are pro¬ 
tected. 

Hy-dro-zo'a (Gr. hudra ; and zobn, animal). The class of the Cozlenterata, 
which comprises animals constructed after the type of the Hydra. 

IIy-men-op'ter-a (Gr. humen , a membrane; pteron , a wing). An order of 
Insects (comprising Bees, Ants, etc.) characterized by the possession of four 
membranous wings. 

IIy'oid (Gr. y ; eidos, form). The bone which supports the tongue in Ver¬ 
tebrates, and derives its name from its resemblance in man to the Greek 
letter y. 

Hy'po-stome (Gr. hupo, under; stoma, mouth). The upper lip, or “ labrum,” 
of certain Crustacea {e. g., Trilobites). 

IIy-ra-coid'e-a (Gr. hurax, a shrew; eidos, form). An order of the Mam¬ 
malia constituted for the reception of the single genus Hyrax. 

Ioh-thy-o-dor'y-lite (Gr. ichihus , fish; doru , spear; lithos, stone). The 
fossil fin-spines of Fishes. 


336 


GLOSSARY. 


Ich-thy-o-mor'pha (Gr. ichthus ; morphe, shape). An order of Amphibians, 
often called TJrodela, comprising the fish-like Newts, etc. 

Ich-thy-oph-thi'ra (Gr. ichthus ; phtheir, a louse). An order of Crustacea 
comprising animals which are parasitic upon Fishes. 

Ich-thy-op'si-da (Gr. ichthus: opsis, appearance). The primary division of 
Vertebrata, comprising the Fishes and Amphibia. Often spoken of as the 
Branchiate Vertebrata. 

Ich-thy-op-ter-yg'i-a (Gr. ichthus; pterux , wing). An extinct order of 
Reptiles. 

Ich-thy-o-sau'ri-a (Gr. ichthus; saura , lizard). Synonymous with Ichthy- 
opterygia. 

Il'i-um. The haunch-bone, one of the bones of the pelvic arch in the higher 
Y ertebrates. 

I-ma'go (Lat. for an image or apparition). The perfect insect, after it has 
undergone its metamorphoses. 

Im'bri-oa-ted. Applied to scales or plates which overlap one another like 
tiles. 

In-ci'sor (Lat. incido , I cut). The cutting teeth fixed in the intermaxillary 
bones of the Mammalia, and the corresponding teeth in the lower jaw. 

In-e-qui-lat'er-al. Having the two sides unequal, as in the case of the 
shells of the ordinary bivalves ( Lamellibranchiata ). When applied to the 
shells of the Foraminifera , it implies that the convolutions of the shell do 
not lie in the same .plane, but are obliquely wound round an axis. 

In-e'qui-valve. Composed of two unequal pieces or valves. 

In-fun-dib' u-LUii (Lat. for funnel). The tube formed by the coalescence or 
apposition of the epipodia in the Cephalopoda —commonly termed the 
“ tunnel,” or “ siphon.” 

In-fu-so ri-a (Lat. infusum , an infusion). A class of Protozoa , so called be¬ 
cause they are often developed in organic infusions. 

Ix'guin-al (Lat. inguen , groin). Connected with, or situated upon, the groin. 

Ix-o-per-cu-la'ta (Lat. %n, without; operculum, a lid). The division of pul- 
monate Gasteropoda in which there is no shelly or horny plate (operculum) 
by which the shell is closed when the animal is withdrawn within it. 

In-sec'ta (Lat. inseco , I cut into). The class of Articulate animals commonly 
known as Insects. 

In-sec-tiv'o-ra (Lat. insectum , an insect; voro, I devour). An order of 
Mammals. 

In-sec-tiv'o-rotjs. Living upon Insects. 

In-ses-so'res (Lat. insideo , I sit upon). The order of the Perching Birds, 
often called Passeres. 

Ln-ter-am-bu-la'cra (Lat. inter , between; ambulacrum, that which serves 
for walking). The rows of plates in an Echinoderm which are not per¬ 
forated for the emission of the “tube-feet.” 

In-ter-max-il'la;, or Pr^:-max-il'l^e (Lat. inter, between; pros, before; 
maxilla, the jaw). The two bones which are situated between the two 
superior maxillae in Vertebrata. In man, and some monkeys, the praemax- 
illae anchylose with the maxillae, so as to be irrecognizable in the adult. 

In-tus-sus-cep'tiox (Lat. intus, within; suscipio, I take up). The act of 
taking foreign matter into a living being. 

Ix-ver-te-brPta (Lat. in, without; vertebra, a bone of the back). Animals 
without a spinal column or backbone. 

Is'chi-um (Gr. ischion, the hip). One of the bones of the pelvic arch in Ver¬ 
tebrates. 

I-sop'o-da (Gr. isos, equal; podes , feet). An order of Crustacea in which the 
feet are like one another and equal. 

Ju'gu-lar (Lat. jugulum, the throat). Connected with, or placed upon, the 
throat. Applied to the ventral fins of fishes when they are placed beneath 
or in advance of the pectorals. 

Kai-no-zo'io (Gr. hainos, recent ; zoe, life). The Tertiary period in Geology, 


GLOSSARY. 


337 


comprising tliose formations in which the organic remains approximate 
more or less closely to the existing fauna and flora. 

Ker'a-tode (Gr. her a?, horn; eidos, form). The horny substance of which 
the skeleton of many sponges is made up. 

Ker-a-to'sa. The division of Sponges in which the skeleton is composed 
of keratode. 

La^bi-ttm (Lat. for lip). Restricted to the lower lip of Articulate animals. 

La'brum (Lat. for lip). Restricted to the upper lip of Articulate animals. 

Lab-y-rinth-o-dox'ti-a (Gr. laburinthos, a labyrinth; odous, tooth). An 
extinct order of Amphibia , so called from the complex microscopic structure 
of the teeth. 

Lac-er-til'i-a (Lat. lacerta , a lizard). An order of Eeptilia comprising the 
Lizards and Slow-worms. 

L-e-mo-dip'o-da (Gr. laimos , throat; die, twice; podes, feet). An order of 
Crustacea , so called because they have two feet placed far forward, as it 
were under the throat. 

La-mel-li-branch-i-a'ta (Lat. lamella , a plate; Gr. bragchia, gills). The 
class of Mollusca , comprising the ordinary bivalves, characterized by the 
possession of lamellar gills. 

La-itel-li-ros'tres (Lat. lamella , a plate; rostrum, beak). The flat-billed 
Swimming Birds ( Natatores ), such as Ducks, Geese, Swans, etc. 

Lar'va (Lat. for a mask). The insect in its first stage after its emergence 
from the egg, when it is usually very different from the adult. 

Lar'ynx. The upper part of the" windpipe, forming a cavity with appropriate 
muscles and cartilages, situated beneath the hyoid bone, and concerned in 
Mammals in the production of vocal sounds. 

Lex-tic'u-lar (Lat. lens, a bean). Shaped like a biconvex lens. 

Lep-i-dop'te-ra (Gr. lepis, a scale; pteron , a wing). An order of Insects, 
comprising Butterflies and MotliSj characterized by possessing four wings 
which are usually covered with minute scales. 

Lep-i-do'ta (Gr. lepidotos, covered with scales). Formerly applied to the 
order Dipnoi , containing the Mud-fishes ( Lepidosiren •). 

Lep-to-car'di-a (Gr. leptos, slender, small; lcardia , heart). The name given 
by Muller to the order oi Fishes comprising the Lancelet, now called Pha- 
ryngobranchii. 

Lig-a-men'tum nu'cha: (Fr. nuque , the nape of the neck). The band of elastic 
fibres by which the -weight of the head in Mammalia is supported. 

Lix'gual (Lat. lingua, the tongue). Connected with the tongue. 

Lin'gu-la (Lat. lingula, a little tongue). The upper flexible portion of the 
labium or lower lip in Insects. 

Lis-sen-ceph'a-la (Gr. lissos, smooth; egJcephalos, brain). A primary division 
of Mammalia, according to Owen, in which the cerebral hemispheres are 
smooth or have few convolutions. 

Lith'o-cysts (Gr. lithos, a stone; Tcustis, a cyst). The sense-organs or “ mar¬ 
ginal bodies ” of the Lucernarida or Steganophthalmate Medusae. 

Lox-gi-pen-na't^e (Lat. longus , long; penna, wing). A group of the Nata¬ 
torial Birds. 

Lon-gi-ros'tres (Lat. longus ; rostrum, beak). A group of the Wading Birds. 

Lopii'-o-phore (Gr. lophos, a crest; and phero, I carry). The disc or stage 
upon which the tentacles of the Polyzoa are borne. 

Loph-u-rop'o-da (Gr. lophouros, having stiff hairs; and podes , feet). An 
order of Crustacea. 

Lo-ri'ca (Lat. for a breast-plate). Applied to the protective case with which 
certain Infusoria are provided.. 

Lor-i-ca'ta (Lat. lorica. a cuirass). The division of Reptiles comprising the 
Chelonia and Crocodilia , in which bony plates are developed in the skin 
{derma). 

Lc-cer-nar'i-da (Lat. lucerna, a lamp). An order of the Hydrozoa. 

Litm'bar (Lat. lumbus , loin). Connected with the loins. 

Luxate (Lat. luna, moon). Crescentic in shape. 


338 


GLOSSARY. 


Ly-en-ceph'a-la (Gr. luo, I loose; egkepkalos, brain). A primary division 
of Mammals, according to Owen. 

Mac-ro-dac'ty-li (Gr. makros , long; daktulos , a finger). A group of the 
Wading Birds. 

Ma-cru'ra (Gr. makros, long; oura, tail). A tribe of Decapod Crustaceans 
with long tails (e. g., the Lobster, Shrimp, etc.). 

Mad-re-por'i-form. Perforated with small holes, like a coral; applied to the 
tubercle by which the ambulacral system of the Echinoderms mostly com¬ 
municates with the exterior. 

Mal-a-co-derm'a-ta. 

Mal-a-cos'tra-ca (Gr. malakos, soft; ostrakon, shell). A division of Crus¬ 
tacea. Originally applied by Aristotle to the entire class Crustacea , because 
their shells were softer than those of the Mollusca. 

Mal-loph'a-ga (Gr. mallos, a fleece; phago , I eat). An order of Insects 
which are mostly parasitic upon birds. 

Mam-ma'lia (Lat. mamma, the breast). The class of Vertebrate animals 
which suckle their young. 

Man'di-ble (Lat. mandibulum, a jaw). The upper pair of jaws in Insects *, 
also applied to one of the pairs of jaws in Crustacea and Spiders, to the beak 
of Cephalopoda, the lower jaw of Vertebrates, etc. 

Man'tle. The external integument of most of the Mollusca, which is largely 
developed, and forms a cloak in which the viscera are protected. Techni¬ 
cally called the “ pallium.” 

Ma-nu'bri-um (Lat. for a handle). The polypite which is suspended from 
the roof of tlie swimming-bell of a Medusa, or from the gonocalyx of a 
medusiform gonophore among the Hydrozoa. 

Ma'nus (Lat. for the hand). Tne hana of the higher Vertebrates. 

Mar-sip-o-branch'i-i (Gr. marsipos, a pouch; bragchia, gills). The order of 
Pishes comprising the Hag-fishes and Lampreys, with pouch-like gills. 

Mar-su-pi-a'li-a (Lat. marsupium , a pouch). An order of Mammals in which 
the females mostly have an abdominal pouch in which the young are carried. 

Mas'tax (Gr. for mouth). The muscular pharynx or “buccal funnel” into 
which the mouth opens in most of the Rotifera. 

Mas-ti-ca'to-ry (Lat. mastico, I chew). Applied to parts adapted for chewing. 

Max-il'l/E (Lat. for jaws). The inferior pair or pairs of jaws in the Arthro- 
poda (Insects, Crustacea, etc.) ; The upper jaw-bones of Vertebrates. 

Max-il'li-pedes (Lat. maxilla,, jaws; pes, the foot). The limbs in Crustacea 
and Myriapoda which are converted into masticatory organs, and are com¬ 
monly called “ foot-jaws.” 

Me-dul'la (Lat. for marrow). Applied to the marrow of bones, or to the 
spinal cord, with or without the adjective “ spinalis .” 

Me-du's.e. An order of Hydrozoa, commonly known as Jelly-fishes ( Disco - 
phora, or Acalephce ), so called because of the resemblance of their tentacles 
to the snaky hair of the Medusa. Many Medusa are now known to be 
merely the gonophores of Hydrozoa. 

Me-du'si-form. Resembling a Medusa in shape. 

Me-du'soid. Like a Medusa ; used substantively to designate the medusiform 
gonophores of the Hydrozoa. 

Mem-bra'na nic'ti-tans (Lat. nicto, I wink). The third eyelid of Birds, etc. 

Men'tum (Lat. for the chin). The basal portion of the labium or lower lip 
in Insects. 

Me-ro-stom'a-ta (Gr. meron, thigh; stoma , mouth). An order of Crustacea 
in which the appendages which are placed round the mouth, and which 
officiate as jaws, have their free extremities developed into walking or pre¬ 
hensile organs. 

Mes-en-te'ri-es (Gr. mesos, intermediate; enteron, intestine). In a restricted 
sense, the vertical plates which divide the somatic cavity of a Sea-anemone 
( Actinia ) into chambers. 

Mes-o-po'di-um (Gr. mesos, middle; pous, foot). The middle portion of the 
“foot” of Molluscs. 


GLOSSARY. 


339 


Mes-o-ster'num (Gr. mesos , intermediate: sternon , the breast-bone). The 
middle portion of the sternum, intervening between the attachment of the 
second pair of ribs and the xiphoid cartilage ( xiphisternum ). 

Mes-o-tho'rax (Gr. mesos; and thorax , the chest). The middle ring of the 
thorax in Insects. 

Mes-o-zo'ic (Gr. mesos / zoe , life). The Secondary period in Geology. 
Met-a-car'pus (Gr. meta, after; karpos , the wrist). The bones which form 
the “ root of the hand,” and intervene between the wrist and the fingers. 
Met-a-mor'pho-sis (Gr. meta, implying change; morphe, shape). The changes 
of form which certain animals "undergo in passing from tneir younger to 
their fully-grown condition. 

Met-a-po'di-um (Gr. meta , after; pous , the foot). The posterior lobe of the 
foot in Mollusca ; often called the “ operculigerous lobe,” because it de¬ 
velops the operculum when this structure is present. 

Me-tas'to ma (Gr. meta, after; stoma, mouth). The plate which closes the 
mouth posteriorly in the Crustacea . 

Met-a-tar'sus (Gr. meta, after; tarsos, the instep). The bones which inter¬ 
vene between the bones of the ankle ( tarsus ) and the digits in the hind-foot 
of the higher Vertebrates. 

Met-a-tho'rax (Gr. meta y after; thorax , the chest). The posterior ring of 
the thorax in Insects. 

Mi-met'io (Gr. mimetikos , imitative). Applied to organs or animals which 
resemble each other in external appearance, but not in essential structure. 
Mo'lars (Lat. mola, a mill). The “ grinders ” in man, or the teeth in diphyo- 
dont Mammals which are not preceded by milk-teeth. 

Mol-lus'oa (Lat. mollis , soft). The sub-kingdom which includes the Shell¬ 
fish proper, the Polyzoa , the Tunicata } and the Lamp-shells; so called from 
the generally soft nature of their bodies. 

Mol-lus-ooi'da {Mollusca ; Gr. eidos , form). The lower division of the Mol 
lusca, comprising the Polyzoa, Tunicata , and Brachiopoda. 

Monads (Gr. monas , unity). Microscopical organisms of an extremely simple 
character, developed in organic infusions. 

Mo-noc'u-lous (Gr. monos , single ; Lat. oculus, eye). Possessed of only one 
eye. 

Mon-o-delph'i-a (Gr. monos , single; delphus, womb). The division of Mam¬ 
malia in which the uterus is single. 

Mo-n(e'ci-ous (Gr. monos, single; oikos, house). Applied to individuals in 
which the sexes are united. 

Mon-o-my'a-ry (Gr. monos, single; mus , muscle). Applied to those bivalves 
( Lamellibranchiata) in which the shell is closed by a single adductor muscle. 
Mon-o-phy'o-dont (Gr. monos ; phuo, I generate ; odous, tooth). Applied to 
those Mammals in which only a single set of teeth is ever developed. 
Mon-o-thal'a-mous (Gr. monos ; and thalamos , chamber). Possessing only a 
single chamber. Applied to the shells of Foraminifera and Mollusca. 
Mon-o-trem'a-ta (Gr. monos ; trema , aperture). The order of Mammals com¬ 
prising the Duck-mole and Echidna , in which the intestinal canal opens 
mto a “ cloaca ” common to the ducts of the urinary and generative organs. 
Mul-ti-loc'u-lar (Lat. multi , many; loculus , a little purse). Divided into 
many chambers. 

Mul'ti-valve. Applied to shells which are composed of many pieces. 
Mul-ton'gu-la (Lat. multi , many; ungula, hoof). The division of Perisso- 
dactyle Ungulates, in which each foot has more than a single hoof. 

My'e-lon (Gr. muelos, marrow). The spinal cord of Vertebrates. 
Myr-i-ap'o-da (Gr. murioi , ten thousand; podes, feet). A class of Arthropoda 
comprising the Centipedes and their allies, characterized by their numerous 
feet. 

Na'cre-ous (Fr. nacre. mother-of-pearl, originally Oriental). Pearly; of the 
texture of mother-of-pearl. 

Nat-a-to'res (Lat. nare, to swim). The order of the Swimming Birds. 
Na'ta-to-ry (Lat. nare, to swim). Formed for swimming. 


340 


GLOSSARY. 


Nau'ti-loii>. Resembling the shell of the Nautilus in shape. 

Nech-o-cajl'y-ces. . . .. 

Nech-o-ca'lyx (Gr. necho, I swim; Icalux, cup). The swimmmg-beU or 
“ disc” of a Medusa or Jelly-fish. . . 

Nem-a-tel'mi-a (Gr. riema, thread; helmins, a worm). The division of Scole- 
cida comprising the Round-worms, Thread-worms, etc. 

Ne-mat'o-cysts (Gr. riema, thread; leustis , a bag). The thread-cells of the 
Codenterata. (See Cnidae.) 

Neh-a-to'da. 

Nem-a-toid'e-a (Gr. riema , thread; eidos , form). An order of Scolecida com¬ 
prising the Thread-worms, Vinegar-eels, etc. 

Ne-hat'o-piiores (Gr. riema, thread \phero, I carry). Caecal processes found 
on the coenosarc of certain of the Sertularida , containing numerous thread- 
cells at their extremities. 

Ne-mer'ti-da (Gr. Nemertes , proper name). A division of the Turbellarian 
Worms , commonly called “ Ribbon-worms.” 

Nerv'ures (Lat. nervus , a sinew). The ribs which support the membranous 
wings of insects. 

Neu'ral (Gr. neuron, a nerve). Connected with the nervous system. 

.Neu-ra-poph' y-sis (Gr. neuron , a nerve; apophusis, a projecting part). The 
“ spinous process ” of a vertebra, or the process formed at the point of 
junction of the neural arches. 

Neur-o-po'di-tjm (Gr. neuron , a nerve; pous, the foot). The ventral or in¬ 
ferior division of the “foot tubercle” of an Annelide / often called the 
“ventral oar.” 

Neu-rop'te-ra (Gr. neuron / and pteron, a wing). An order of Insects charac¬ 
terized by four membranous wings with numerous reticulated nervures 
(<e. g., Dragon-flies). 

Neuter (Lat. for neither the one nor the other). Having no fully-developed 
sex. 

Nid-i-fi-ca'tion (Lat. nidus , a nest; facio , I mate). The building of a nest. 

Noc-tur'nal (Lat. nox, night). Applied to animals which are active by night. 

Nor'mal (Lat. norma, a rule). Conforming to the ordinary standard. > 

No-to-branch-i-a'ta (Gr. not os, the back; and bragchia, gills). Carrying the 
gills upon the back; applied to a division of the Annelida. 

No'to-chord (Gr. notos, back ; chorde , string). A cellular rod which is devel¬ 
oped in the embryo of Vertebrates immediately beneath the spinal cord, 
and which is usually replaced in the adult by the vertebral column. Often 
it is spoken of as the “ chorda dorsalis.” 

No-to-po'di-um (Gr. notos, the back; and pous, the foot). The dorsal divis¬ 
ion of one of the foot-tubercles or parapodia of an Annelide ; often called 
the “ dorsal oar.” 

Nu'cle-a-ted. Possessing a nucleus or central particle. 

Nu-cle'o-lus. 1. The minute solid particle in the interior of the nucleus of 
some cells. 2. The minute spherical particle attached to the exterior of 
the “ nucleus,” or ovary, of certain Infusoria , performing the functions of 
a testicle. 

Nu'cle-us (Lat. nucleus, a kernel). 1. The solid or vesicular body found in 
many cells. 2. The solid rod, or band-shaped body found in the interior 
of many of the Protozoa, and having, in certain of them, the functions of 
an ovary. S. The “madreporiform tubercle” of the Echinodermata. 4. 
The embryonic shell which is retained to form the apex of the adult shell 
in many of the Mollusca. 

Nu-di-branch-i-a'ta (Lat. nudus, naked; and Gr. bragcliia , gills). An order 
of the Gasteropoda in which the gills are naked. 

Nymphs. The active pupae of certain Insects. 

Oc-cip'i-tal. Connected with the occiput, or the back part of the head. 

O-CE-AN'io. Applied to animals which innabit the open ocean (= pelagic). 

O-cel'li (Lat. diminutive of oculus, eye). The simple eyes of many Echino- 
denns, Spiders, Crustaceans, Molluscs, etc. 


GLOSSARY. 


341 


Oo-top'o-da (Gr. octo, eight: pons, foot). The trihe of Cuttle-fishes with 
eight arms attached to the head. 

O-don-to-ce'ti (Gr. odous, tooth ; ketos, whale). The “toothed” Whales, in 
contradistinction to the “ whalebone ’’’Whales. 

O-don'toid (Gr. odous ; eidos , form). The “ odontoid process ” is the centrum 
or body of the first cervical vertebra (atlas). It is detached from the atlas, 
and is usually anchylosed with the second cervical vertebra (axis), and it 
forms the pivot upon which the head rotates. 

O-don'to-phore (Gr. odous , tooth ; phero , I carry). The so-called “tongue” 
or masticatory apparatus of Gasteropoda, Pteropoda , and Cephalopoda. 

(E-soph'a-gus. Tne gullet or tube leading from the mouth to the stomach. 

Ol-i-go-cii^'ta (Gr. oligoi, few; chaite, hair). An order of Annelida, com¬ 
prising the Earth-worms, in which there are few bristles. 

O-ma'sum (Lat. for bullock’s tripe). The third stomach of Ruminants, com¬ 
monly called the psalterium , or many-plies. 

Om-ni v o-rous (Lat. omnia , everything; voro, I devour). Feeding indis¬ 
criminately upon all sorts of food. 

O-per-cu-la'ta (Lat. operculum , a lid). A division of pulmonate Gasterop¬ 
oda , in which the shell is closed hy an operculum. 

O-per'cu-lum. A horny or shelly plate developed in certain Mollusca upon 
the hinder part of the foot, and serving to close the aperture of the shell 
when the animal is retracted within it; also the lid of the shell of a Bala- 
nus or Acorn-shell; also the chain of flat bones which cover the gills in 
many fishes. 

O-piiid'i-a (Gr. ophidion , a little snake). The order of Reptiles comprising 
the Snakes. 

Opii-i-do-ba-tra'chi-a (Gr. ophis, a snake; batrachos , a frog). Sometimes ap¬ 
plied to the order of Snake-like Amphibians comprising the Cceeilice. 

Oph-i-o-hor'pha (Gr. ophis; morphe , shape). The order of Amphibia com¬ 
prising the Ccecilice. 

Oph-i-u-roid'e-a (Gr. ophis, a snake; oura, tail* eidos, form). An order of 
Echinodermata comprising the Brittle-stars and Sand-stars. 

O-pis-tho-branch-i-a'ta (Gr. opisthen, behind; bragchia, g ills). A division 
of Gasteropoda in which the gills are placed on the posterior part of the 
hody. 

O-pis-tho-cce'lous (Gr. opisthen , behind; Icoilos, hollow). Applied to verte¬ 
brae, the bodies of which are nollow or concave behind. 

Oral (Lat. os. mouth). Connected with the mouth. 

Or-ni-tho-del phi-a (Gr. ornis, a bird ; delphus, womb). The primary divis¬ 
ion of Mammals comprising the Monotremata. 

Or-thop'te-ra (Gr. orthos, straight; pteron, wing). An order of Insects. 

Os'cu-la (Lat. diminutive of os, mouth). 1. The large apertures by which a 
sponge is perforated (“ exhalant apertures ”). 2. The suckers with which 

tne To&niada (Tape-worms and Cystic Worms) are provided. 

Os-sio'u-la (Lat. diminutive of os, bone). Literally, small hones. Often used 
to designate any hard structures of small'size, such as the calcareous plates 
in the integument of the Star-fishes. 

Os-tra-co'da (Gr. ostrahon, a shell; and eidos, form). An order of small 
Crustaceans which are enclosed in Divalve shells. 

Ot'o-liths (Gr. ous, ear; and lithos, stone). The calcareous bodies connected 
with the sense of hearing, even in its most rudimentary form. 

O-va'ri-an Ves-i-cles or Cap'sules. The generative buds of the Sertularida. 

O'va-ry (O-va'ri-um). The organ by whicn ova are produced. 

O-vip'a-rous (Lat. ovum, an egg; and pario, I bring forth). Applied to ani¬ 
mals which bring forth eggs, in contradistinction to those whicn bring forth 
their young alive. 

O-vi-pos'i-tor (Lat. ovum; and pono, I place). The organ possessed by 
some insects, by means of which the eggs are placed in a position suitable 
for their development. 

O'vi-sac. The external bag or sac in which certain of the Invertebrates 
carry their eggs after they are extruded from the body. 


342 


GLOSSARY. 


O-vo-vi-yip'a-rous (Lat. ovum , egg; vivus , alive; pario, I pro luce). Ap¬ 
plied to animals which retain their eggs within the body until they are 
hatched. 

O'vum (Lat. for an egg). The germ produced within the ovary, and capable 
under certain conditions of being developed into a new individual. 

Pach-y-der'ma-ta (Gr. pachus , thick; derma , skin). An old Mammalian 
order constituted by Cuvier for the reception of the Rhinoceros, Hippopota¬ 
mus, Elephant, etc. 

Pa-lje-on-tol'o-gy (Gr .palaios, ancient j onta, beings; and logos, discourse). 
The science of fossil remains or of extinct organized beings. 

Pa- 1 m£-o-zo'io (Gr. palaios , ancient; and zoe, life;. Applied to the oldest of 
the great geological epochs. 

Pal'li-al. 

Pal-li-o-bran-chi-a'ta (Lat. pallium ; and Gr. bragchia , gills). An old name 
for the Brachiopoda , founded upon the belief that the system of tubes in 
the mantle constituted the gills. 

Pal'li-im (Lat. pallium , a cloak). The mantle of the Mollusca. Pallial: 
relating to the mantle. Pallial line or impression : the line left in the dead 
shell by the muscular margin of the mantle. Pallial shell: a shell which 
is secreted by, or contained within, the mantle, such as the “ bone ” of the 
Cuttle-fishes. 

Pal'pi (Lat. palpo , I touch). Processes supposed to be organs of touch, de¬ 
veloped from certain of the oral appendages in Insects, Spiders, and Crus¬ 
tacea, and from the sides of the mouth in the Acephalous Molluscs. 

Pa-pil'la (Lat. for nipple). A minute soft prominence. 

Par-a-po'di-a (Gr. para , beside ; podes , feet). The unarticulated lateral loco¬ 
motive processes or “foot-tubercles” of many of the Annelida. 

Pa-ri'e-tal (Lat. paries , a wall). Connected with the walls of a cavity or of 

the body. 

Pa-ri-e-to-splanch'nic (Lat. paries; Gr. splagchna, viscera). Applied to 
one of the nervous ganglia or the Mollusca, which supplies the walls of the 
body and the viscera. 

Par-then-o-gen'e-sis (Gr. parthenos , a virgin ; and genesis , production). 
Strictly speaking, confined to the production of new individuals from virgin 
females by means of ova without the intervention of a male. Sometimes 
used also to designate a sexual reproduction by gemmation or fission. 

Pat-a-gi'um (Lat. for the border of a dress). Applied to the expansion of the 
integument by which Bats, Flying Squirrels, and other animals support 
themselves in the air. 

Pa-tel'la (Lat. for the knee-cap or knee-pan). A sesamoid bone devel¬ 
oped in the tendon of insertion of the great extensor muscles of the thigh. 

Pecti-nate (Lat. pecten , a comb). Comb-like; applied to the gills of certain 
Gasteropods , hence called Pectmibranchiata. 

Pec'to-ral (Lat. pectus , chest). Connected with, or placed upon, the chest. 

Pe'dal (Lat. pes , the foot). Connected with the foot of Mollusca. 

Ped-i-cel-lari-^e (Lat. pedicellus , a louse). Certain singular appendages 
found in many Echinoderms , attached to the surface of the body, and re¬ 
sembling a little beak or forceps supported on a stalk. 

Ped'i-cle (Lat. dimin. of pes, the foot). A little stem. 

Ped-i-pal'pi (Lat. pes, foot; and palpo , I feel). An order of Arachnida 
comprising the Scorpions, etc. 

Pe-dun'cle (Lat. pedunculus , a stem or stalk). In a restricted sense applied 
to the muscular process by which certain Brachiopods are attached, and to 
the stem which bears the body (capitulum) in Barnacles. 

Pe-dun'cu-late. Possessing a peduncle. 

Pe-dun'cu-la-ted. 

Pe-lag'io (Gr. pelagos, sea). Inhabiting the open ocean. 

Pel'vis (Lat. for basin). Applied, from analogy, to the basal portion of the 
cup (calyx) of Crinoids. The body arch with which the hind-limbs are 
connected in Vertebrates. 


GLOSSARY. 


343 


Per-en-ni-bran-chi-a'ta (Lai. perennis, perpetual; Gr. bragchia, gills). Ap¬ 
plied to those Amphibia in which the gills are permanently retained through¬ 
out life. 

Per-ga-men-ta'ceotts (Lat. pergamena, parchment). Of the texture of parch¬ 
ment. 

Per-i-car'di-um (Gr. peri, around; lcardia, heart). The serous membrane in 
which the heart is contained. 

Per'i-derm (Gr. peri, around ; and derma, skin). The hard cuticular layer 
which is developed by the ccenosarc of certain of the Hydrozoa. 

Per-i-gas'tric (Gr. pert , around : and gaster, stomach). The perigastric space 
is the cavity which surrounds the stomach and other viscera, corresponding 
to the abdominal cavity of the higher animals. 

r er-i-ostra-cum (Gr. peri; and ostrakon, shell). The layer of epidermis 
which covers the shell in most of the Mollusca. 

Per'i-plast (Gr. peri; and p lasso, I mould). The intercellular substance or 
matrix in which the organized structures of a tissue are embedded. 

Per'i-some (Gr .peri ; and soma, body). The coriaceous or calcareous integu¬ 
ment of the Echinodermata. 

Per-is-so-dac'ty-la (Gr .perissos, uneven; daJctulos , finger). Applied to those 
Hoofed Quadrupeds ( Ungulata) in which the feet have an uneven number 
of toes. 

Per'i-stome (Gr. peri; and stoma, mouth). The space which intervenes be¬ 
tween the mouth and the margin of the calyx in Vorticella ; also the space 
between the mouth and the tentacles in a sea-anemone ( Actinia ); also the 
lip or margin of the mouth of a univalve shell. 

Per-i-vis'ce-ral (Gr. peri / and Lat. viscera, the internal organs). Applied 
to the space surrounding the viscera. 

Pet'a-loid. Shaped like the petal of a flower. 

Piia-lan'ges (Gr. phalagx, a row). The small bones composing the digits of 
the higher Vertebrata. Normally each digit has three phalanges. 

Phar-yn-go-bran'chi-i (Gr. pharugx, pharynx; bragchia, gills). The order 
of Fishes comprising only the Lancelet. 

Phar'ynx. The dilated commencement of the gullet. 

Phrag'ma-cone (Gr. phragma, a partition ; and konos, a cone). The cham¬ 
bered portion of the internal shell of a Belemnite. 

Phy-lac-to-lem'a-ta (Gr. phulasso, I guard; and laimos, throat). The divi¬ 
sion of Polyzoa in which the mouth is provided with the arched valvular 
process known as the “ epistome.” 

Phyl'lo-cysts (Gr. phullon, leaf; and Icustis, a cyst). The cavities in the in¬ 
terior of the “ hyarophyllia ” of certain of the Oceanic Hydrozoa. 

Phyl-lop'o-da (Gy. phullon, leaf; and pous, foot). An order of Crustacea. 

Phy-o-gem-ma'ri-a (Gr. phuo, I produce ; and Lat. gemma, bud). The small 
gonoblastidia of Velelta , one of the Physophoridce. 

Phy-so-gra'da (Gr. phusa, bellows or air-bladder; and Lat. gradior, I walk). 
Applied formerly to the Physophoridce , an order of Oceanic Hydrozoa , in 
which a “ float ” is present. 

Phy-so-phor'i-d^e (Gr. phusa, air-bladder; and p hero, I carry). An order of 
Oceanic Hydrozoa. 

Phy'toid (Gr. phuton, a plant; and eidos, form). Plant-like. 

Phy-toph'a-gous (Gr. phuton, a plant; and phago, I eat). Plant-eating, or 
herbivorous. 

Pin'n^e. 

Pin'nate (Lat. pinna, a feather). Feather-shaped, or possessing lateral pro¬ 
cesses. 

Pin-ni-gra'da (Lat. pinna, a feather; gradior, 1 walk). The group of Car¬ 
nivora, comprising the Seals and Walruses, adapted for aquatic life. Often 
called Pinnipedia. 

Pin'nd-ljb (Lat. dim. of pinna.) The lateral processes of the arras of Cri- 
noids. 

Pis'ces (Lat. niseis, a fish). The class of Vertebrates comprising the Fishes. 

Pla-cen'ta (Lat. for a cake.) The “ after-birth,” or the organ by which a 


344 


GLOSSARY. 


vascular connection is established in the higher Mammalia between the 
mother and the foetus. 

Pla-cen'tal. Possessing a placenta, or connected with the placenta. 

Plac'oid (Gr. plax, a plate ; eidos, form). Applied to the irregular bony 
plates, grains, or spines, which are found in the skin of various fishes 
( Elasmobranchii). 

Pla-gi-os'to-mi (Gr. plagios, transverse; stoma , mouth). The Sharks and 
Rays, in which the mouth is transverse, and is placed on the under surface 
of the head. 

Pla-nar'i-da (Gr. plane, wandering). A sub-order of the Turbellaria. 

Plan-ti-gra'da. 

Plant'i-grade (Lat. planta , the sole of the foot; gradior , I walk). Applying 
the sole of the foot to the ground in walking. 

Plan'u-la (Lat. planus, fiat). -The oval ciliated embryo of certain of the Hy~ 
drozoa. 

Plas'tron. The lower or ventral portion of the bony case of the Chelonians. 

Plat-y-el'mi-a (Gr. platus , broad ; and helmins, an intestinal worm). The 
division of Scoledda comprising the Tape-worms, etc. 

Plat-y-rhi'na (Gr .platus, broad ; rhines , nostrils). A group of the Quadru- 
mana. 

Ple-si-o-satt'rus (Gr. plesios , near to ; and saurus , lizard). 

Pleura (Gr. for the side). The serous membrane covering the lung in the 
air-breathing Vertebrates. 

Pleu'ron (Gr. pleuron , a rib). The lateral extensions of the shell of Crustacea . 

Plu'te-us (Lat. for a pent-house). The larval form of the Echinoidea. 

Pneu-mat'ic (Gr. pneuma, air). Filled with air. 

Pneu-mat'o-cyst (Gr. pneuma, air; and kustis, cyst). The air-sac or float of 
certain of the Oceanic Hydrozoa (Physophoridce). 

Pneu-mat'o-phore (Gr. pneuma, air ; suadphero, I carry). The proximal dilata¬ 
tion Of the ccenosarc in the Physophoridce which surrounds the pneumatocyst. 

Pneu-mo-skel'e-ton (Gr. pneuma; and skeUtos, dry). The hard structures 
which are connected with the breathing organs {e'ig., the shell of Molluscs). 

Pod-oph-thal'mata (Gr. pous, foot; ana oplithalrnos , eye). The division of 
Crustacea in which the eyes are borne at the end oi long foot-stalks. 

Pod-o-som'a-ta (Gr. pous, foot; soma, body). An order of Arachnida. 

Po-eph'a-ga (Gr .poe, grass; phago, I eat)/ A group of the Marsupials. 

Pois'ers. 

Pol'lex (Lat. for the thumb). The innermost of the five normal digits of the 
anterior limb of the higher Vertebrates. In man, the thumb. 

Pol-y-cys-ti'na (Gr. polus, many; and kustis, a cyst). An order of Protozoa, 
with foraminated siliceous shells. 

Po-lyg'a-mous (Gr. polus : and gamos, marriage). 

Pol-y-gas'tri-ca (Gr. polus; and gaster, stomach). The name applied by 
Ehrenberg to the Infusoria, under the belief that they possessed many 
stomachs. 

Pol'y-pa-ry (Gr. and pario, I produce). The hard chitinous cover¬ 

ing secretea by many of the Hydrozoa. 

Poltpe (Gr. polus, many; pous, foot). Restricted to the single individual 
of a simple Actinozobn, such as a Sea-anemone, or to the separate zooids of 
a compound Actinozobn. Often applied indiscriminately to any of the 
Coelenterata. or even to the Polyzoa. 

Pol'y-pide. The separate zooid of a Polyzoon. 

Pol-yp'i-dom. The dermal system of a colony of a Hydrozobn, or Polyzobn. 

Pol'y-pite. The separate zooid of a Hydrozoon. 

Pol'y-stome (Gr. polus, many; and stoma, mouth). Having many mouths ; 
applied to the Acinetce among the Protozoa. 

Pol-y-thal'a-mous (Gr. polus; and thalamos. chamber). Having many 
chambers ; applied to the shells of Foraminijera and Cephalopoda. 

Pol-y-zo'a (Gr. polus ; and zo'Jn, animal). A division of the Molluscoida, 
comprising compound animals, such as the Sea-mat. Sometimes called 
Bryozoa. 


GLOSSARY. 


345 


Pol-y-zo-a'ri-um. The dermal system of the colony of a Polyzoon (= Polypi- 
dom). 

Por-cel-la'ne-ous. Of the texture of porcelain. 

Po-rif'e-ra (Lat. porus, a pore; and fero, I carry. Sometimes used to desig¬ 
nate the Forammifera, or the Sponges. 

Post'a-nal (Lat. post, behind; anus, the fundament). Situated behind the 
anus. 

Post-ce-so-phag'e-al (Gr. oisophagos, the gullet). Situated behind the gullet. 

Post-o'ral (Lat. os, mouth). Situated behind the mouth. 

Prj3-max-i.l Las. ( See Intermaxillse.) 

I’r^e-mo'lars (Lat. pros, before; molares, the grinders). The molar teeth of 
Mammals which succeed the molars of the milk-set of teeth. In man, the 
bicuspid teeth. 

Prjb-ce-so-phag’e-al. Situated in front of the gullet. 

Pr^-ster'nujj (Gr . sternon, the breast). The anterior portion of the breast¬ 
bone, corresponding with the manubrium sterni of human anatomy, and 
extending as far as the point of articulation of the second rib. 

Pres-si-ros tres (Lat . press us, compressed; rostrum, beak). A group of the 
Grallatorial Birds. 

Prob-os-cid'e-a (Lat. proboscis, the snout). The order of Mammals com¬ 
prising the Elephants. 

Pro-bos cis (Lat. or Gr. for the snout). Applied to the spiral trunk of Lepidop- 
terous Insects, to the projecting mouth of certain Grinoids, and to the cen¬ 
tral polypite in the Medusae. 

Pro-cce’lous (Gr. pro, in front; Jcoilos, hollow). Applied to vertebrae, the 
bodies of which are hollow or concave in front. 

Pro-glot'tis (Gr. for the tip of the tongue). The generative segment or joint 
of a Tape-worm. 

Pro'legs. The false abdominal feet of Caterpillars. 

Pro-na'tion (Lat. prouus, lying on the face, prone). The act of turning the 
palm of the hand downward. 

Pro-po'di-um (Gr. pro, before; pous, foot). The anterior part of the foot in 
Molluscs. 

Pro-sco'lex (Gr. pro, before; scolex, worm). The first embryonic stage of a 
Tape-worm. 

Pros-o-bran-ciii-a'ta (Gr. proso, in advance of; bragchia, gills). A division 
of Gasteropodous Molluscs in which the gills are situated in advance of the 
heart. 

Pro-so'ma (Gr. pro, before; soma, body). The anterior part of the bodv. 

Pro-tho'rax ^Gr. pro; and thorax, chest). The anterior ring of the thorax 
of insects. 

Pro-topii'y-ta (Gr. protos, first; and phuton, plant). The lowest division of 
plants. 

Pro'to-plasm (Gr. protos; and plasso, I mould). The elementary basis of 
organized tissues. Sometimes used synonymously for the “ sarcode ” of 
the Protozoa. 

Pro-top'o-dite (Gr. protos; and pous, foot). The basal segment of the typi¬ 
cal limb of a Crustacean. 

Pro-to-zo'a (Gr. protos; and zo'^n, animal). The lowest division of the ani¬ 
mal kingdom. 

Pro-ven-tric'u-lus (Lat. pro, in front of; ventriculus, dim. of venter, belly). 
The cardiac portion of tne stomach of Birds. 

Prox'i-mal (Lat. proximus, next). The slowly-growing, comparatively-fixed 
extremity of a limb or of an organism. 

Psal-te'ri-um (Lat. for a stringed instrument). The third stomach of Ru¬ 
minants. ( See Omasum.) 

Pseu-dem'bry-o (Gr. pseudes, false; embruon, embryo;. The larval form of 
an Echinoderm. 

Pseu-do-bran'ciii-a (Gr. pseudes, false ; bragchia, gills). A supplementary gill 
found in certain fishes, which receives arterialized blood only, and does 
not, therefore, assist in respiration. 


346 


GLOSSARY. 


Pseu-do-ele'mal (Gr. pseudes , false; and Tiaima , blood). Applied to the 
vascular system of Annelida. 

Pseu'do-hearts. Certain contractile cavities connected with the atrial sys¬ 
tem of Brachiopoda , and long considered to be hearts. 

PsEu-DO-NAv-i-cELEiE (Gr. pseudes, false ; and Navieula , a genus of Diatoms). 
The embryonic forms of the Gregarinidce , so called from their resemblance 
in shape to the Navieula. 

Pseu-do-po'di-a (Gr. pseudes ; and pous, foot). The extensions of the body- 
substance which are put forth by the Rhizopoda at will, and which serve 
for locomotion and prehension. 

Pseu-do'va (Gr. pseudes ; (Lat. ovum , egg). The egg-like bodies from which 
the young of the viviparous Aphis are produced. 

Pteii-op'o-da (Gr. pteron , wing; and pous, foot). A class of the Mollusca 
which swim by means of tins attached near the head. 

Pter-o-sau'ri-a (Gr. pteron , wing; saura, lizard). An extinct order of Rep¬ 
tiles. 

Pu'bis (Lat. pubes, hair). The share-bone; one of the bones which enter 
into the composition of the pelvic arch of Vertebrates. 

Pue-mo-gas-ter-op'o-da (= Pulmonifera). 

Pul-mo-na'ri-a. A division of Arachnida which breathe by means of pulmo¬ 
nary sacs. 

Pul'mo-na-ry. 

Pul'mo-nate. Possessing lungs. 

Pul-mo-nif'e-ra (Lat. pulmo , a lung; and fero, I carry). The division of 
Mollusca which breathe by means of a pulmonary chamber. 

Pu'pa (Lat. for a doll). The stage of an insect immediately preceding its ap¬ 
pearance in a perfect condition. In the pupa-stage it is usually quiescent— 
when it is often called a “ chrysalis; ” but it is sometimes active—when it 
is often called a “ nymph.” 

Py-lo'rus (Gr. puloros , a gatekeeper). The valvular aperture between the 
stomach and the intestines. 

Pyr'i-form (Lat. pirum or pyrum , a pear; and forma , form). Pear-shaped. 

Quad-ru-ma'na (Lat. quatuor , four • manus, hand). The order of Mammals 
comprising the Apes, Monkeys, Baboons, Lemurs, etc. 

Quad-ru-ma'nous. 

Ra-di-a'ta (Lat. radius , a ray). Formerly applied to a large number of ani¬ 
mals which are now placed*in separate sub-kingdoms (e. g., the Ceelenierata , 
the Echinodermata , the Infusoria , etc.). 

Ra-di-o-la'ri-a (Lat. radius , a ray). A division of Protozoa. 

Ra'di-us (Lat. for a spoke or ray). The innermost of the two bones of the fore¬ 
arm of the higher Vertebrates. It carries the thumb, when present, and 
corresponds with the tibia of the hind-limb. 

Ra'mus (Lat. for a branch). Applied to each half or branch of the lower jaw 
or mandible of Vertebrates. 

Rap-to'res (Lat. rapio, I plunder). The order of the birds of Prey. 

Rap-to'ri-al. 

Ra-so'res (Lat. rado, I scratch). The order of the Scratching Birds (Fowls, 
Pigeons, etc.). 

Ra-ti't^e (Lat. ratis , a raft). Applied by Huxley to the Cursorial Buds, which 
do not ny, and have therefore a raft-like sternum without any median keel. 

Rectum (Lat. rectus , straight). The terminal portion of the intestinal canal, 
opening at the surface of the body at the anus. 

Rep-til'i-a (Lat. repo, I crawl). The class of the Vertebrata comprising the 
Tortoises,, Snakes, Lizards, Crocodiles, etc. 

Re-tic-u-lari-a (Lat. reticulum, a net). Employed by Dr. Carpenter to desig¬ 
nate those Protozoa , such as the Foraminifera , in which the pseudopodia 
run into one another and form a network. 

Re-tio'u-lum (Lat. for a net). The second division of the complex stomach 
of Ruminants, often called the “ honey-comb bag.” 


GLOSSARY. 


347 


Re-versed'. Applied to spiral univalves, in which the direction of the spiral 
is the reverse of the normal— i. e., sinistral. 

Rhi-zoph'a«ga (Gr. rhiza, root; phago , I eat). A group of the Marsupials. 

Rhi-zop'o-da (Gr. rhiza, a root; and pous, foot). The division of Protozoa 
comprising all those which are capable of emitting pseudopodia. 

Rhyn'cho-lites (Gr. rhugchos, beak; and lithos, stone). Beak-shaped fos¬ 
sils, consisting of the mandibles of Cephalopoda. 

Ro-den'ti-a (Lat. rodo, I gnaw). An order of the Mammals; often called 
Glires (Lat. glis, a dormouse). 

Rostrum (Lat. rostrum , beak). The “beak” or suctorial organ formed by 
the appendages of the mouth in certain insects. 

Ro-ta-Wri-a (= Rotifera). 

Ro-tif'e-ra (Lat. rota, wheel; and fero, I carry'*. A class of the Scoltdda 
( Annuloida ) characterized by a ciliated “ trochal disc.” 

Ru-go'sa (Lat. rugosus, wrinkled). An extinct order of Corals. 

Ru'men (Lat. for the throat). The first cavity of the complex stomach of Ru¬ 
minants : often called the “ paunch.” 

Ru-mi-nan ti-a (Lat. ruminor , I chew the cud). The group of Hoofed Quad¬ 
rupeds ( Ungulata) which “ ruminate ” or chew the cud. 

Sa'crum. The vertebrae (usually anchylosed) •which unite with the haunch- 
bones (ilia) to form the pelvis. 

Sand-ca-nal (= Stone-ca-nal). The tube by which water is conveyed from 
the exterior to the ambulacral system of the Echinodermata. 

Sar'code (Gr. sarx, flesh; eidos , form). The jellv-like substance of which 
the bodies of Protozoa are composed. It is an albuminous body containing 
oil-granules, and is sometimes called “ animal protoplasm.” 

Sar'coids (Gr. sarx; and eidos, form). The separate amcebiform particles 
which in the aggregate make up the “flesh” ot a Sponge. 

Sau'ri-a (Gr. saura , a lizard). Any lizard-like Reptile is often spoken of as 
a “ Saurian: ” but the term is sometimes restricted to the Crocodiles alone, 
or to the Crocodiles and Lacertilians. 

Sau-ro-ba-tra'chi-a (Gr. saura ; batrachos , frog). Sometimes applied to the 
order of the tailed Amphibians ( Urodela). 

Sau-rop'si-da (Gr. saura ; and op sis, appearance). The name given by Hux¬ 
ley to the two classes of the Birds ana Reptiles collectively. 

Sau-rop-ter-yg'i-a (Gr. saura ; and pterux, wing). An extinct order of Rep¬ 
tiles, called by Huxley Plesiosauria. from the typical genus Plesiosaurus. 

Sau-ru'r^e (Gr. saura ; and oura, tail). The extinct order of Birds compris¬ 
ing only the Archaeopteryx. 

Scan-so'res (Lat. scando, I climb). The order of the Climbing Birds (Par¬ 
rots, Woodpeckers, etc.). 

Sca-phog'na-thite (Gr . skaphos, boat; and gnathos, jaw). The boat-shaped 
appendage (epipodite) of the second pair of maxillae in the Lobster ; the 
function of which is to spoon out the water from the branchial chamber. 

Soap u-la (Lat. for shoulder-blade). The shoulder-blade of the pectoral arch 
of Vertebrates : in a restricted sense, the row of plates in the cup of Cri- 
noids, which give origin to the arms, and are usually called the “axillary 
radials.” 

Sole-ren'chy-ma (Gr. skier os, hard; and egchuma , tissue). The calcareous 
tissue of which a coral is composed. 

Sole'rites (Gr. sJcleros). The calcareous spicules which are scattered in the 
soft tissues of certain Actinozoa. 

Scler-o-ba'sio (Gr. skleros , hard; basis, pedestal). The coral which is pro¬ 
duced by the outer surface of the integument in certain Actinozoa ( e. g.. 
Red Coral), and forms a solid axis which is invested by the soft parts of the 
animal. It is called “ foot-secretion” by Mr. Dana. 

Soler-o-der'mic (Gr. skleros; and derma , skin). Applied to the corallum 
which is deposited within the tissues of certain Actinozoa , and is called 
“ tissue-secretion” by Mr. Dana. 

8ole-rot' io (Gr. skleros, hard). The outer dense fibrous coat of the eye. 


348 


GLOSSARY. 


Sco-leo'i-da (Gr. sholex , worm). A division of the Annuloida. 

Sco'lex (Gr. for worm). The embryonic stage of a Tape-worm, iormerly 
known as a “Cystic Worm.” . , . n 

Sou'ta (Lat. scutum, a shield). Applied to any shield-like plates ; especially 
to those which are developed in the integument of many Reptnes. 

Se-la'chi-a or Se-la'chi-i (Gr .selachos, a cartilaginous fish, probably a shark). 
The sub-order of Elasmobranchii, comprising the Sharks and Dog-fishes. 

Se'pi-o-staire (Lat. and Gr. sepia, the cuttle-fish.) The internal shell of the 
Cuttle-fish, commonly known as the “ cuttle-bone.” 

Sep'ta. Partitions. 

Ser-pen'ti-form. Resembling a serpent in shape. 

Ser-tu-lar'i-da (Lat. sertum, a wreath). An order of Hydrozoa. 

Ses'sile (Lat. sedeo, I sit). Not supported upon a stalk or peduncle ; attached 
by a base. 

Se't.e (Lat. for bristles). Bristles, or long stiff hairs. 

Se-tif'er-ous. Supporting bristles. 

Se-tig'er-ous (— Setiferous). 

Se'tose. Bristly. < 

Si-lic'eous (Lat. silex, flint). Composed of flint. 

Sin'is-tral (Lat. sinistra, the left hand). Left-handed; applied to the di¬ 
rection of the spiral in certain shells, which are said to be “ reversed.” 

Si'xus (Lat. sinus, a bay). A dilated vein or blood-receptacle. 

Si'phox (Gr. siphon, a tube). Applied to the respiratory tubes in the Mol- 
lusca ; also to other tubes of different functions. 

Si-phon-oph'o-ra (Gr. siphon ; sm&phero, I carry). A division of the Hydro¬ 
zoa, comprising the Oceanic forms ( Calycophoridae and Physophoridoe). 

Si-phon-o-stom'a-ta (Gr. siphon ; and stoma, mouth). The division of G-aster- 
opodous Molluscs, in which the aperture of the shell is not “ entire,” but 
possesses a notch or tube for the emission of the respiratory siphon. 

Si-phun'cle (Lat. siphunculus, a little tube). The tube which connects to¬ 
gether the various chambers of the shell of certain Cephalopoda (e. g ., the 
Pearly Nautilus). 

Si-phun’-cu-loi'de-a (Lat. siphunculus, a little siphon). A class of Anarthrop - 
oda ( Annulosa). 

Si-re'ni-a (Gr. seiren, a mermaid). The order of Mammalia comprising the 
Dugongs and Manatees. 

Sol-id-un'gu-la (Lat. solidus, solid; ungula, a hoof). The group of Hoofed 
Quadrupeds comprising the Horse, Ass, and Zebra, in which each foot has 
only a single solid hoof. Often called Solipedia. 

So-mat'io (Gr. soma, body). Connected with the body. 

So-mat'o-cyst (Gr. soma ; and Tcustis, a cyst). A peculiar cavity in the coeno- 
sarc of the Calycophoridce {Hydrozoa). 

So'hite (Gr. soma). A single segment in the body of an Articulate animal. 

Sper-ma'ri-um. The organ in which spermatozoa are produced. 

Sper-mat'o-phores (Gr. sperma, seed; phero, I carry). The cylindrical cap¬ 
sules of the Cephalopoda, which carry the spermatozoa; sometimes called 
the “ moving filaments of Needham.” 

Sper-ma-to-zo a (Gr. sperma, seed; and zoon, animal). The microscopic fila- 
' ments which form the essential generative element of the male. 

Spi'cu-la (Lat. spiculum, a point). Pointed needle-shaped bodies. 

Spin'ner-ets. The organs by means of which Spiders and Caterpillars spin 
threads. 

Spi'ra-cles (Lat. spiro, I breathe). The breathing-pores, or apertures of the 
breathing-tubes (tracheae) of Insects. Also the single nostril of the Hag- 
fishes, the “ blow-hole ” of Cetaceans, etc. 

Splanch-xo-skel'e-tox (Gr. splagchna, viscera ; skeletos, dry). The hard 
structures occasionally developed in connection with the internal organs or 
viscera. 

Sponge-par'ti-cles. ( See Sarcoids). 

Spon'gi-da (Gr. spoggos , a sponge). The division of Protozoa commonly 
known as sponges! 




GLOSSARY. 


349 


Spores (Gr. spora, seed). Germs, usually of plants; in a restricted sense, 
the reproductive “ gemmules” of certain Sponges. 

Spo'ro-sacs (Gr. spora, seed ; and sahkos. a bag). The simple generative buds 
of certain Hydrozoa , in which the medusoid structure is not developed. 

Squa'ma-ta (Lat. squama ? a scale). The division of Reptiles comprising the 
Ophidia and Lacertilia in which the integument develops horny scales, but 
there are no dermal ossifications. 

Stat'o-blasts (Gr. statos, stationary; blastos , bud). Certain reproductive buds 
developed in the interior of Polyzoa , but not liberated until the death of 
the parent organism. 

Steg-an-oph-thal'ma-ta (Gr. steganos , covered; and ophthalmos, the eye). 
Applied by Edward Forbes to certain Medusae, in which the sense-organs 
(“marginal bodies”) are protected by a sort of hood. The Steganopldhal- 
mata are now separated from the true Medusidce , and placed in a separate 
division under the name Lucernarida. 

Stel-ler'i-da (Lat. Stella, star;. Sometimes applied to designate the order 
of the Star-fishes. 

Stel'li-form. Star-shaped. 

Stem'ma-ta (Gr. stemma , garland). The simple eyes, or “ ocelli,” of certain 
animals, such as Insects, Spiders, and Crustacea. 

Ster'num (Gr. sternon). The breast-bone. 

Stig'ma-ta. The breathing-pores in Insects and Arachnida. 

Sto'lon (Gr. stolos , a sending-forth). Off-shoots.—The connecting processes 
of sarcode, in Foraminifera; the connecting tube in the social Ascidians ; 
the processes sent out by the coenosarc of certain Actinozoa. 

Sto-map'o-da (Gr. stoma , mouth j pous, foot). An order of Crustacea. 

Stom'a-tode (Gr. stoma ; eidos , form). Possessing a mouth. The Infusoria 
are thus often called the Stomatode Protozoa. 

Strep-sip'te-ra (Gr. strepho , I twist; and pteron , wing). An order of In¬ 
sects in which the anterior wings are represented by twisted rudiments. 

Streps-i-rhi'na (Gr. strepho , I twist; rines, nostrils). A group of the Quad- 
rumana, often spoken of as Prosimioe. 

Strob'i-la (Gr. strobilos , a top, or fir-cone). The adult Tape-worm with its 
generative segments or proglottides; also applied to one of the stages in 
the life history of the Lucernarida. 

Sty'li-form (Lat. stylus , a pointed instrument; forma , form). Pointed in 
shape. 

Sub-cal-ca're-ous. Somewhat calcareous. 

Sub-cen'tral. Nearly central, but not quite. 

Sub-pe-dun'ou-late. Supported upon a very short stem. 

Sub-ses sile. Nearly sessile, or without a stalk. 

Suc-to'ri-al. 

Su-pi-na'tion (Lat. supinus , lying with the face upward). The act of turn¬ 
ing the hand with tne palm upward. 

S u-pra-<e-so-phag'e-al. 

Su'ture (Lat. suo , I sew). The line of junction of two parts which are im¬ 
movably connected together. Applied to the line where the whorls of a 
univalve shell join one another; also to the lines made upon the exterior 
of the shell of a chambered Cephalopod by the margins of the septa.. 

Swim'mer-ets. The limbs of Crustacea , which are adapted for swimming. 

Sym'piiy-sis (Gr. sumphusis , a growing together). Union of two bones in 
which there is no motion, or but a very limited amount. 

Syn-ap-tic'u-l^: (Gr. sunapto , I fasten together). Transverse props some¬ 
times found in Corals, extending across the loculi like the bars of a 
grate. 

Sys'to-le (Gr. sustello , I contract). Applied to the contraction of any con¬ 
tractile cavity, especially the heart. 

Tab'u-LuE (Lat. tabula , a tablet). Horizontal plates or floors found in some 
Corals, extending across the cavity of the “ theca,” from side to side. 

Tac'tile (Lat. tango, I touch). Connected with the sense of touch. 

16 


350 


GLOSSARY. 


T^e-ni'a-da (Gr. tainia, a ribbon). The division of Scolecida comprising the 
Tape-worms. 

Tjs'ni-oid (Gr. tainia ; and eidos, form). Ribbon-shaped, like a Tape-worm. 

Tar-so-met-a-tar'sus. The single bone in the leg of Birds produced by the 
union and anchylosis of the lower or distal portion of the tarsus with the 
whole of the metatarsus. 

Tarsus (Gr. tarsos , the flat of the foot). The small bones which form the 
ankle (or “ instep ” of man), and which correspond with the wrist (carpus) 
of the anterior limb. 

Tec-ti-bran-ciii-a'ta (Lat. tectus , covered; and Gr. bragchia, gills). A divi¬ 
sion of Opisthobranchiate Gasteropoda in which the gills are protected by 
the mantle. 

Teg-u-ment'ar-t (Lat. tegumentum , a covering). Connected with the integu¬ 
ment or skin. 

Tel-e-os'te-i (Gr. teleios , perfect; osteon , bone). The order of the u Bony ” 
Fishes. 

Tel'son (Gr. ielson, a limit). The last joint in the abdomen of Crustacea ; 
variously regarded as a segment without appendages, or as an azygos ap¬ 
pendage. 

Ten-u-j-ros'tres (Lat. tenuis , slender; rostrum , beak). A group of the Perch¬ 
ing Birds characterized by their slender beaks. 

Ter gum (Lat. for back), the dorsal arc of the somite of an Arthropod. 

Ter-res'tri-al. 

Ter-ric'o-la (Lat. terra , earth; and colo, I inhabit). Employed occasionally 
to designate the Earth-worms ( Lumbncidce ). 

Test (Lat. testa , shell). The shell of Mollusca , which are for this reason 
sometimes called u Testacea also, the calcareous case of Echinoderms ; 
also, the thick, leathery, outer tunic in the Tunicata. 

Tes-ta'ceous. Provided with a shell or hard covering. 

Testis (Lat. testis , the testicle). The organ in the male animal which pro¬ 
duces the generative fluid or semen. 

Tet-ra-bran-chi-a'ta (Gr. tetra, four; bragchia , gills). The order of Cephalop¬ 
oda, characterized by the possession of four gills. 

Tha-las-si-col'li-da (Gr. thalassa , sea; holla, glue). A division of Protozoa. 

The'ca (Gr. theke, a sneath). A sheath or receptacle. 

The-co-som'a-ta (Gr. theke ; and soma, body). A division of Pteropodous 
Molluscs, in which the body is protected by an external shell. 

The-ri-o-mor'pha (Gr. therion, beast; morpTie, shape). Applied by Owen to 
the order of the Tail-less Amphibians ( Anoura ). 

Tho'rax (Gr. for a breast-plate). The chest. 

Thread-cells. (See Onidse.) 

Thys-a-nu'ra (Gr. thusanoi, fringes ; and our a, tail). An order of Apterous 
Insects. 

Tib'ia (Lat. for a flute). The shin-bone, being the innermost of the two bones 
of the leg, and corresponding with the radius in the anterior extremity. 

To-ti-pal'ma-taj (Lat. totus , whole : palma, the palm of the hand). A group 
of Wading Birds in which the hallux is united to the other toes by mem¬ 
brane, so that the feet are completely webbed. 

Tra-che'a (Gr. traclieia , the wind-pipe). The tube which conveys air to the 
lungs in the air-breathing Vertebrates. 

Tra-che'^e. The breathing-tubes of insects and other articulate animals. 

Tra-che-a'ri-a. The division of Arachnida which breathe by means of tra¬ 
cheae. 

Trem-a-to'da (Gr. trema, a pore; eidos, form). An order of Scolecida. 

Trich'o-oysts (Gr. throe-, hair; and kustis , a cyst). Peculiar cells found in 
certain Infusoria, and very nearly identical with the “ thread-cells ” of 
Ccelenterata. 

Tri-lob'i-ta (Gr. treis, three; lobos, a lobe). An extinct order of Crustaceans. 

Trit-o-zooid (Gr. tritos, third; zoon, animal; and eidos, form). The zooid 
produced by a deuterozooid; that is to say, a zooid of the third genera¬ 
tion. 


GLOSSARY. 


351 


Tro'chal (Gr. trochos, a wheel). Wheel-shaped: applied to the ciliated diso 
of the Rotifera. 

Tro-chan'ter (Gr. trecTio, I run). A process of the upper part of the thigh¬ 
bone (femur) to which are attached the muscles which rotate the limb. 
There may be two, or even three, trochanters present. 

Tro'choid (Gr. trochos, a wheel; and eidos, form). Conical, with a flat base: 
^ applied to the shells of Foraminiftra and Univalve Molluscs. 

Tro'phi (Gr. trophos , a nourisher). The parts of the mouth in insects which 
are concerned in the acquisition and preparation of food. Often called 
“ instrumenta cibaria.” 

Troph'o-some (Gr. trepho, I nourish ; and soma, bodv). Applied collectively 
to the assemblage of the nutritive zooids of any Hydrozobn. 

Trun'ca-ted (Lat. trunco , I shorten). Abruptly cut off; applied to univalve 
shells, the apex of which breaks off, so that the shell becomes “ decol¬ 
lated.” 

Tu-bic'o-la (Lat. tuba, a tube; and cola, I inhabit). The order of Annelida 
which construct a tubular case in which they protect themselves. 

Tu-bic'o-lous. Inhabiting a tube. 

Tu-bu-lar'i-da. 

Tu-xi-ca'ta (Lat. tunica, a cloak). A class of Molluscoida which are envel¬ 
oped in a tough, leathery case or “ test.” 

Tur-bel-la'ri-a (Lat. turbo, I disturb). An order of Scolecid-a. 

Tur'bi-xa-ted (Lat. turbo, a top). Top-shaped; conical, with a round base. 

Ul'na (Gr. olene, the elbow). The outermost of the two bones of the fore¬ 
arm, corresponding with the fibula of the hind-limb. 

Um'bel-late (Lat. umbella, a parasol). Forming an umbel— i. e., a number 
of nearly equal radii , all proceeding from one point. 

Um-bil'i-cus (Lat. for navel). The aperture seen at the base of the axis of 
certain univalve shells, which are then said to be “ perforated” or “ um- 
bilicated.” 

Um'bo (Lat. for the boss of a shield). The beak of a bivalve shell. 

Um-brel'la. The contractile disc of one of the Lucernarida. 

Un'ci-nate (Lat. uncus, a hook). Provided with hooks or bent spines. 

Un-guic'u-late (Lat. unguis, nail). Furnished with claws. 

Un-gu-la'ta (Lat. ungula, hoof). The order of Mammals comprising the 
Hoofed Quadrupeds. 

Un'gu-late. Furnished with expanded nails constituting hoofs. 

U-ni-loc'u-lar (Lat. unus, one ; and loculus, a little purse). Possessing a 
single cavity or chamber. Applied to the shells of Foraminifera and Mol- 
lusca. 

U'ni-valve (Lat. unus, one ; valves, folding-doors). A shell composed of a 
single piece or valve. 

U-ro-de'la (Gr. our a, tail; delos, visible). The order of the tailed Amphi¬ 
bians (Newts, etc.). 

Ur'ti-oa-tixo Cells (Lat. urtica, a nettle). ( See Cnidae.) 

Vao'u-oles (Lat. vacuus, empty). The little cavities formed in the interior 
of many of the Protozoa by the presence of little particles of food, usually 
surrounded by a little water. These are properly called “ food-vacuoles,” 
and were supposed to be stomachs by Ehrenberg. Also the clear spaces 
which are often seen in the tissues of many Ccelenterata. 

Var'i-ces (Lat. varix, a dilated vein). The ridges or spinose lines which 
mark the former position of the mouth in certain univalve shells. 

Vas'cu-lar (Lat. vas, a vessel). Connected with the circulatory system. 

Ve'lum (Lat. for a sail). The membrane which surrounds and partially closes 
the mouth of the “ aisc” of Medusae, or medusiform gonophores. 

Ven'tral (Lat. venter, the stomach). Relating to the inferior surface of the 
body. 

Ven'tri-cle (Lat. dim. of venter, stomach). Applied to one of the cavities of 
the heart, which receives blood from the auricle. 


352 


GLOSSARY. 


Ver'mes (Lat. vermis, a worm). Sometimes employed at the present dayin 
the same, or very nearly the same, sense as Annuloida , or as Annuloida 
plus the Anarthropoda. 

Ver'mi-form (Lat. vermis , worm ; and forma, form). Worm-like. 

Ver'te-bra (Lat. verto, I turn). One of the bony segments of the vertebral 
column or back-bone. 

Ver-te-bra'ta. (Lat. vertebra , a bone of the hack, from vertere , to turn). 
The division of the Animal Kingdom roughly characterized by the posses¬ 
sion of a back-bone. 

Yes'i-cle (Lat. vesica . a bladder). A little sac or cyst. 

Vi-brac'u-la (Lat. vioro, I shake). Long filamentous appendages found in 
many Polyzoa. 

Vib-ri-o'nes (Lat. vibro, I shake). The little moving filaments developed in 
organic infusions. 

Vip-e-ri'na (Lat. vipera , a viper). A group of the Snakes. 

V is'ce-ra. 

Vi-vip'a-rous (Lat. vivus, alive; and pario, I bring forth). Bringing forth 
young alive. 

Whorl. The spiral turn of a univalve shell. 

Xiph-i-ster'num (Gr. xipbos, sword ; sternon , breast-bone). The inferior or 
posterior segment of the sternum, corresponding with the “ xiphoid carti¬ 
lage ” of human anatomy. 

Xiph-o-su'ra (Gr. xipJios , a sword; and our a, tail). An order of Crustacea , 
comprising the Limuli or King-Crabs, characterized by their long sword¬ 
like tails. 

Xy-loph'a-gous (Gr. xulon , wood; and phayo, I eat). Eating wood ; applied 
to certain Mollusca . 

Zo'oid (Gr. zoon , animal; and eidos, form). The more or less completely in¬ 
dependent organisms, produced by gemmation or fission, whether these re¬ 
main attached to one another or are detached and set free. 

Zo'o-phyte (Gr. zoon, animal; phuton , plant). Loosely applied to many 
plant-like animals, such as Sponges, Corals, Sea-anemones, Sea-mats, etc. 

Zo'o-spores (Gr. zoon , animal; and spora , seed). The ciliated locomotive 
germs of some of the lowest forms of plants ( Protophyta ). 


QUESTIONS. 


1. Mention some of the characters of living beings. 

2. What is understood by “ organization ? ” 

3. Define Biology and Zoology. 

4. What characters separate the higher animals from the higher plants ? 

5. How does the nutrition of plants differ from that of animals ? 

6. What is understood by “ classification ? ” 

7. W T hat is the basis of a natural and scientific classification ? 

8. Explain the terms “morphology” and “physiology.” 

9. What is understood by “ sub-kingdoms,” and upon what characters 
are these founded ? 

10. What are the great Physiological functions ? Define these. 

11. Explain the terms “homology ” and “analogy,” and give examples. 

12. What leading characters separate the Invertebrate from the Verte¬ 
brate animals. 

13. What are the chief characters of the Protozoa? 

14. What is sarcode ? 

15. What are cilia, flagella, and pseudopodia? 

16. Mention the three great classes of Protozoa. 

17. What is the structure of a Gregarina , and where would you expect to 
find one? 

18. What structures characterize the Rhizopoda? 

19. Describe an Amoeba. 

20. What is the so-called “ contractile vesicle ? ” 

21. What is meant by “ fission ? ” 

22. How do the pseudopodia of the Foraminifera differ from those of an 
Amoeba ? 

23. What structures are absent in the Foraminifera, which occur in the 
Amoeba ? 

24. What is the nature of the shell of the Foraminifera ? 

25. What differences subsist between a perforated and an imperforate 
shell ? Between a simple and a compound shell ? 

26. Where do Foraminifera mostly occur ? 

27. What is understood by “Distribution in Space” and “Distribution in 
Time ? ” 

28. Mention one or two remarkable fossil Foraminifera. 

29. What is Chalk to a great extent composed of? 

30. What is the nature of the skeleton of the Radiolaria? 

31. Mention some example of the Radiolaria. 



354 


QUESTIONS. 


32. Of what two essential elements is a Sponge composed ? 

33. What is the nature of the “ sponge-flesh ? ” 

34. Describe the circulation of water in a Sponge. 

35. What are the chief variations in the skeleton of Sponges ? 

36. Whence are the Sponges of commerce obtained ? 

37. How do the Infusorian Animalcules derive their name ? 

38. By what leading character are the Infusoria distinguished from the 
other Protozoa ? 

39. Why were the Infusoria formerly called Polygastrica ? 

40. Describe the Bell-animalcule. 

41. What peculiarity of the digestive system characterizes the sub-king¬ 
dom Ccdenterata? 

42. Of what is the body of a Coelenterate animal composed ? 

43. What is a “ thread-cell ? ” 

44. Into what two classes are the Coelenlerata divided, and what charac¬ 
ters distinguish these ? Mention examples of each. 

45. What is understood by “ gemmation ? ” How is a compound animal 
or colony produced ? 

46. What is meant by the term “ zooid ? ” 

47. What is scientifically understood by the terra “ individual ? ” 

48. Define the terms “ polypite,” “ coenosarc,” and “ polypary.” 

49. Give examples of the Hydroid Zoophytes. 

50. Describe shortly the structure of the Hydra. 

51. What is the method of reproduction in the Hydra ? 

52. What peculiarities distinguish the polypary of the Corynida i 

53. Give an example of the Corynida. 

54. What two sets of zooids go to form the colony of a Hydroid Zoo¬ 
phyte ? 

55. Define the terms “ trophosome ” and “gonosome.” 

56. What is a “ gonophore ? ” 

57. What is a “ medusiform gonophore ? ” Why is it so called, and what 
is its general structure ? 

58. Give an example of the Sertnlarida , and mention the differences 
which distinguish their polypary from that of the Corynida. 

59. What is a “hydrotheca?” 

60. Describe the general structure of the reproductive bud of a Cam- 
panularian. 

61. How do the Oceanic Hydrozoa differ from the Hydroid Zoophytes? 

62. What is a “ nectocalyx,” and what is its structure ? 

63. What is a “ bract ? ” 

64. Mention examples of the Oceanic Hydrozoa. 

65. What is the “ float ” or “ pneumatophore ” of the Physophoridce ? 

66. Of what real nature are many of the so-called Medusce or Jelly-fishes ? 

67. What is the general structure of a Medusa , and with what structure 
in the Hydroid Zoophytes does it agree ? 

68. From what circumstance is the name “ naked-eyed ” Medusce derived ? 

69. What are the “marginal bodies ” of the Medusce? 

70. Describe Lucernaria. 

71. Of what nature are the great Sea-blubbers ? 

72. Describe “Hydra-tuba” and its development. 

73. What is the structure of a “Hidden-eyed Medusa” or Sea-blubber, 
and from what circumstance is the former name derived ? 

74. Differences between the naked-eyed and hidden-eyed Medusa) ? 

75. Describe the generative bud of Rhizostoma. 


QUESTIONS. 


355 


76. Give the leading characters of the Aclinozoa. 

77. How does the transverse section of a Hydrozoon differ from that of 
an Actinozoon ? 

78. What is a “ polype? ” 

79. Describe a Sea-anemone. 

80. What are the “ mesenteries ” of a Sea-anemone, and what organs do 
they carry ? 

81. What is a “ coral ? ” 

82. What are the “ septa ” of a coral, and to what part of the living 
animal do they correspond ? 

83. What are coral-reefs, where do they occur most abundantly, and what 
are the chief varieties which occur? 

81. How do the Alcyonaria differ numerically from the Zoantharia ? 

85. Mention some example of the Alcyonaria. 

86. In what Alcyonarian is there a well-developed sclerodermic coral ? 

87. Of what nature is the sclerobasic coral of the Gorgonidce? 

88. Mention a well-known example of the Gorgonidce. 

89. Give the leading characters of the Ctenophora. 

90. What is a “ ctenophore ? ” 

91. Is a nervous system present in any of the Aclinozoa , except in the 
Ctenophora ? 

92. Mention an example of the Ctenophora. 

93. What animals belong to the Echinodermala , and whence is the name 
of the class derived ? 

94. What is understood by “ bi-lateral symmetry ? ” 

95. At what time of life are the Echinoderms bi-laterally symmetrical, 
and what is their condition in this respect when adult ? 

96. What is a water-vascular system, what is it called in this class, and 
what special function does it generally discharge ? 

97. What is the arrangement of the nervous system in Echinoderms ? 

98. What distinguishes the Sea-urchins from other Echinoderms ? 

99. Into how many zones may the test of a living Sea-urchin be divided, 
and how many rows of plates are contained in each zone ? 

100. What are the “ambulacral” and “ inter-ambulacral areas? ” 

101. What plates are always placed at the summit of the shell? 

102. What is the “ madreporiform tubercle? ” 

103. Describe the general nature of the spines and their function. 

104. What are “ pedicellariae ? ” 

105. What are the “ tube-feet ? ” Describe the general arrangement of 
the ‘‘ ambulacral system.” 

106. What is the structure of the circulatory and nervous organs in the 
Echinus ? 

107. Mention a peculiarity in the development of the Echinus. 

108. Give the leading characters of the Star-fishes. 

109. What peculiarities distinguish the arms of Star-fishes ? 

110. What is the structure of the stomach in Star-fishes? 

111. How do the Brittle-stars resemble the true Star-fishes, and how are 
they distinguished ? 

112. What is the structure of the digestive system in Brittle-stars? 

113. What is the essential peculiarity of the Crinoids ? 

114. Mention a living Crinoid which is free when adult, and one which is 
permanently fixed. 

115. What is the general shape of the HolotJmrians , and the nature of 
their integuments ? 


356 


QUESTIONS. 


116. What is the condition of the ambulacral system, and where is the 
“ madreporiform tubercle ” situated ? 

117. What is the mouth surrounded by? 

118. What is the “respiratory tree ” of the Holothurians ? 

119. What characters distinguish the Scolecida ? How are they separated 
from the Echinoderms ? 

120. What is meant by the term Entozoa? 

121. In what relation do the Bladder-worms stand to the Tape-worms ? 

122. What is the structure of an ordinary Tape-worm? 

123. Give the structure of the “head” and of a single joint, and state 
what is the relation of the head to the joints. 

124. State shortly the process of development in a Tape-worm. 

125. What is the “ measles ” of the Pig ? 

126. What are “ hydatids ” in man ? 

127. What are the characters of the Trematode worms ? Mention an ex¬ 
ample. 

128. What is the “ rot ” of Sheep caused by ? 

129. What groups of animals are included in the lurbellaria ? 

130. Give an example of the Acanthocephala , and state the character from 
which the name is derived. 

131. Where do the Gordiacea spend the earlier part of their existence, 
and w r hat is their common name ? 

132. Mention examples of the Nematode worms. 

133. From what do the Wheel-animalcules get their name ? 

134. What is the general size of the Rotifers, and where are they found ? 

135. What marked differences are there between the males and females ? 

136. What are the functions of the ciliated “wheel? ” 

137. Give the general anatomy of a Rotifer. 

138. Give the leading characters of an Annulose animal. 

139. Into what great divisions is the sub-kingdom Annulosa divided, and 
what are the characters of these ? 

140. What is the general structure of one cf the rings of an An- 
nelide ? 

141. What is the “pseudohtemal system” of the Annelida , and to what 
is it believed to correspond ? 

142. What are the characters of the Hirudinca ? 

143. To what does the Medicinal Leech owe its value? 

144. How is locomotion effected in the Leeches ? 

145. How are the Oligochceta distinguished ? 

146. What are the locomotive organs of the Earth-worm? 

147. Of what nature are the breathing-organs of the Tubicola , and where 
are they placed ? 

148. Mention a common Tubicolous Annelide. 

149. To what do the Errantia owe their name, and what are their loco¬ 
motive organs ? 

150. Where are the gills placed in the Errantia ? 

151. What orders of Annelida possess gills, and which have not ? 

152. Give the general characters of Articulate animals. 

153. Give the characters of the Crustacea. 

154. How many segments go to the body of a Crustacean, and into what 
distinct regions may these be distributed ? 

155. What is understood by the “ cephalothorax ? ” 

156. To what section of Crustacea does the Lobster belong ? 

157. What is the “carapace” of the Lobster ? 


QUESTIONS. 


357 


158. What is the part generally called the “tail,” and what is the so- 
called “ head ? ” 

159. What are the “ antennae,” and how many are there in the Lobster 
and in Cimstacea generally ? 

160. What are “foot-jaws,” and why are they so called? 

161. What are “ chelae ? ” 

162. Of what nature are the appendages of the abdomen in the Lobster? 

163. What is the last segment of the abdomen called ? 

164. Describe the gills ot the Lobster. Where are they placed ? 

165. Of what nature is the abdomen of the Hermit-crabs ? 

166. How are the Crabs distinguished from the Lobsters? 

167. By what character does the young Crab approach the Lobster? 

168. Give an example of the Isopoda ? 

169. What is the character of the appendages of the mouth in the King- 
Crabs ? 

170. What is the structure of a Trilobite ? 

171. What is the nature of the shell of the Ostracode Crustaceans? 

172. What change do the Cirripedes undergo in passing from the larval 
to the adult condition ? 

173. What are the two types of the Cirripedes ? Give examples. 

174. Give the general characters of the Arachnida? 

175. What is the structure of the mandibles of the Spiders? Of the 
Scorpions ? 

176. To what do the mandibles of the Arachnida correspond? 

177. Of what nature are the breathing-organs of the Arachnida ? 

178. What is the structure of trachea; ? Of pulmonary sacs ? 

179. What are the organs of vision in the Arachnida ? 

180. What are the habits of the Mites ? Give examples. 

181. By what structure do the Scorpions inflict wounds? 

182. What is the condition of the abdomen in Scorpions ? In Spiders? 

183. By means of what organs do the Spiders spin webs? 

184. What are the general characters of the Myriapoda ? 

185. What is the general condition of the young Myriapod? 

186. What are the distinctions between the Centipedes and Millipedes? 

187. What is the number of legs in Pauropus? 

188. What are the general characters of Insects ? 

189. What organs are carried by the head in Insects ? 

190. How many segments form the thorax, and what appendages do they 
always carry ? What appendages do they sometimes carry ? 

191. What are “ nervures ? ” 

192. How many rings generally go to the abdomen of Insects ? What 
appendages (if any) do these support ? 

193. What are the chief modifications in the organs of the mouth in 
Insects ? 

194. Describe the digestive system of an Insect? 

195. How is the circulation carried on ? 

196. Of what nature are the breathing-organs ? 

197. Of what nature are the eyes in Insects ? 

198. What is understood by the “metamorphosis” of an Insect ? 

199. What are the chief differences in the metamorphoses of Insects? 

200. What peculiarity distinguishes the adult state of Insects which 
undergo no metamorphosis ? 

201. What is understood by the terms “larva,” “pupa,” and “imago?” 

202. What is a “ chrysalis ? ” A “ cocoon ?•” 


358 


QUESTIONS. 


203. What are the more important Insects which pass through no meta¬ 
morphosis ? 

204. The chief characters of the Hemiptera? Give examples. 

205. What are “ hemelytra ? ” 

203. The chief characters of the Orthoptera? Give examples. 

207! The chief characters of the Neuroptera? Give examples.. 

208^ What members compose a colony of White Ants or Termites ? 

209] The chief characters of the Aphaniptera ? Give an example. 

210. The chief characters of the Diptera? Give examples. 

211. The chief characters of the Lepidoptera? 

212. Characters of the larvae of Lepidoptera? 

213. What characters distinguish Butterflies and Moths respectively? 

214. Chief characters of Hymenoptera ? Give examples. 

215. Give some account of the social communities of Bees and Ants ? 

216. What is the condition of the wings in Strepsiptera ? 

217. Chief characters of Coleoptei'a ? Give examples. 

218. What are “ elytra ? ” 

219. Mention a useful Beetle. 

220. Chief characters of the Mollusca ? 

221. Condition of nervous system in Mollusks ? Of circulatory system ? 
Of breathing-organs ? Of digestive system ? 

222. Primary divisions of Mollusca, and the characters of these ? 

223. Chief characters of the Polyzoa ? 

224. Explain the term “ polvpide ? ” 

225. How is the polypide of a Polyzoon distinguished from the polypite 
of a Hydrozoon ? 

226. Structure of a single “ polypide. ” 

227. What are “ bird’s-head processes,” and to what may they be com¬ 
pared ? 

228. What general distinction is there between the fresh-water and marine 
Polyzoa ? 

229. Chief characters of Tunicata ? 

230. Nature of the “ test ? ” 

231. Structure of the heart in Tunicata ? 

232. Distinctions between simple, social, and compound Tunicates ? 

233. Chief characters of Brachiopoda ? 

234. Nature of the shell, as compared with that of Bivalves ? 

235. Structure and nature of the “ arms ? ” 

236. Chief characters of the Lamellibranchiata ? Give examples. 

237. Nature and uses of the “foot?” 

238. Nature, uses, and number of the “ adductor muscles ? ” 

239. What are the “ muscular impressions ” and the “ pallial line ? ” 

240. Structure and mode of opening, and connection between, the 
valves ? 

241. Structure of the respiratory organs ? 

242. Nature and uses of the “respiratory siphons ?,” 

243. Condition of circulatory system ? Of digestive system ? 

244. Condition of young when first hatched? 

245. Chief characters of the Gasteropoda ? Give examples. Why spoken 
of as “ univalves /” 

246. What is the “ operculum ? ” 

247. Compare the Gasteropoda with the Lamellibranchiata as regards the 
head. 

248. What is the nature of the “ odontophore ? ” 


QUESTIONS. 


359 


249. Condition of the heart and breathing-organs ? 

250. What divisions of the Gasteropoda may be founded on the nature of 
the breathing-organs ? 

251. Condition of the young water-breathing Gasteropod? 

252. Structure and modifications of the shell in Gasteropods ? 

253. What are the two leading conditions of the mouth of the shell ? 

254. General characters of the Nudibranchiata ? 

255. Nature of the foot in the Heteropoda ? 

256. General characters of the air-breathing Gasteropods ? 

257. General characters of the Pteropoda? 

258. General characters of the Cephalopoda? 

259. Nature of the “ arms ” and their suckers in the Cuttle-fishes ? 

260. Structure of the “ funnel ? ” 

261. Nature of the ink-bag? What livingCephalopod is without an ink- 
bag? 

262. Nature of the breathing-organs ? Of the circulatory organs ? Of 
the respiratory process ? Of the nervous system ? 

263. Peculiarities in the reproductive process in the Cuttle-fishes ? 

264. Nature of the internal shell of the Cuttle-fishes ? 

265. What two living Cephalopods possess an external shell, and what 
are the differences between these? 

266. Characters of the Dibranchiate Cephalopods ? Give examples. 

267. Describe the shell of the Argonaut? 

268. Characters of the Tetrabranchiate Cephalopods ? 

269. Describe the shell of the Pearly Nautilus ? 

270. Mention some fossil forms allied to the Pearly Nautilus? 

271. General characters of the Vertebrata? 

272. What is the “notochord?” 

273. General structure of a “vertebra?” 

274. Regions generally recognizable in the vertebral column ? 

275. General structure of the fore-limb? 

276. General structure of the hind-limb? 

277. General structure of the digestive system ? 

278. Source of the blood ? Nature of the “ blood-corpuscles ? ” 

279. What Vertebrate animal has no heart? 

280. General nature of the respiratory organs ? 

281. What is the difference between a gill and a lung? 

282. General structure of the nervous system ? 

283. Define the terms “ oviparous,” “ viviparous,” and “ ovo-viviparous.” 

284. Into what primary sections are the Vertebrata divided by Huxley? 

285. What are the five classes of Vertebrates ? 

286. General characters of Fishes ? 

287. Chief forms of scales? 

288. Nature of the “ lateral line ? ” 

289. Form of the vertebrae of a Fish ? 

290. Position and connections of the ribs ? 

291. Nature of the “ interspinous bones ? ” 

292. Nature and position of the limbs of Fishes ? 

293. Distinction between the “ paired ” and “ median fins ? ” 

294. Number and names of the median fins ? 

295. Difference between homocercal and heterocercal tail? 

296. What are the “ rays ? ” Difference between “ soft rays ” an<J 
“ spinous rays ? ” 

297. What are the “ pyloric caeca ? ” 


360 


QUESTIONS. 


298. General arrangement of the gills in a Bony Fish ? 

299. Structure of the heart and course of the circulation in a typical Fish ? 

300. What is the “ swim-bladder,” and to what does it correspond ? 

301. Nature of the swim-bladder in the Mud-fish ? 

302. Condition of the organ of hearing ? of the nose ? 

303. In what Fishes does the nose open behind into the throat ? 

304. General characters of the Lancelet ? 

305. General characters of the Marsipobranchii ? Give examples. 

306. Nature of the respiratory organs in the Lampreys ? 

30*7. General characters of Teleostd? Give examples. 

308. General characters of the Ganoidei ? Give examples. 

309. Condition of the vertebrae in the Bony Pike ? 

310. General characters of the Elasmobranchii ? Give examples. 

311. General characters of the Dipnoi ? 

312. Distribution of the Mud-fishes? 

313. General characters of the class Amphibia ? 

314. Nature of the metamorphosis in Amphibians? 

315. General characters of the Ophiomorpha? Give examples. 

316. General characters of Urodela? Give examples. 

317. Explain the terms “ perennibranchiate ” and “ caducibranchiate.” 

318. Distinctions between Tailed Amphibians and Lizards? 

319. General characters of the Anoura ? Give examples. 

320. Phenomena of the development of a Frog? What general zoologi¬ 
cal law is illustrated thereby ? 

321. General chax-acters of the Sauropsida ? 

322. General characters of Reptiles ? 

323. Structure of the lower jaw, and its connections with the skull ? 

324. General nature of the teeth ? 

325. In what Reptiles are the teeth sunk in sockets ? 

326. How does the intestine terminate in Reptiles ? 

327. Structure of the heart and course of the circulation in Reptiles 
generally ? 

328. Condition of the heart in the Crocodiles ? 

329. General characters of the Chtlonia ? Give examples ? 

330. Leading peculiarities in the skeleton of Chdonia ? 

331. Chief groups of Chelonians ? Give examples. 

332. General characters of the Ophidia ? 

333. Condition of the limbs in Snakes ? 

334. Mode of progression in Snakes ? 

335. Structure of the tongue ? of the eye? 

336. Structure and connections of the lower jaw ? 

337. General structure and function of the teeth ? 

338. Nature of the teeth in the non-venomous and poisonous Snakes 
respectively ? 

339. Examples of harmless Snakes ? 

340. Examples of poisonous Snakes ? 

341. General characters of the Lacertilia? Give examples. 

342. Characters which separate the snake-like Lizards from the true 
Serpents ? 

343. Peculiarities of the Flying Dragon ? 

344. General characters of the Crocodilia ? 

345. Differences between Crocodiles and Alligators, and the geographical 
distribution of each ? 

346. Peculiarity of the Gavial, and its geographical distribution ? 


QUESTIONS. 


361 


347. Leading characters of the Ichthyopterygia ? 

348. Characters separating Plesiosaurus from Ichthyosaurus ? 

349. Leading characters of Pterosauria ? 

350. General characters of Birds ? 

351. General structure of a quill feather ? 

352. Peculiarity of the feathers of the Ostrich ? 

353. Characters of the backbone in Birds ? 

354. Nature and position of the “ ploughshare ” bone ? 

355. Structure of the beak ? 

356. Nature of the “ sternal ribs ? ” 

357. Form of the sternum in Birds which fly ? In those which do not 

fly? 

358. Structure of the shoulder-girdle ? 

359. Nature and function of the “merry-thought? ” 

860. General structure of the fore-limb or wing ? 

361. General structure of the hind-limb? 

362. Nature of the “ tarso-metatarsus ? ” 

363. Number and position of the toes ? 

364. What bird possesses only two toes ? 

365. What is the “ cere ? ” 

366. General structure of the digestive system in Birds ? 

367. Condition of gizzard in flesh-eating and grain-eating Birds respec¬ 
tively ? 

368. What are the “ intestinal caeca ? ” 

369. Structure and peculiarities of the lungs ? 

370. Structure and functions of the air-sacs ? 

371. What is meant by a bone being “ pneumatic ? ” 

372.. In what cases are the bones not pneumatic ? 

373. General structure of the heart and course of the circulation in Birds ? 

374. What is “ incubation,” and why are Birds specially adapted for this 
process ? 

375. What differences subsist in the condition of the young bird at birth ? 

376. What peculiarities distinguish the eye of Birds? 

377. What is the “membrana nictitans ? ” 

378. What peculiarities distinguish the ear of Birds ? 

879. What Birds have a rudimentary external ear? 

380. General characters of the Natatores? Give examples. 

381. General characters of the Grallatores? Give examples. 

382. General characters of the Cursores? 

383. Mention some of the more remarkable Cursorial Birds, and state 
something as to their peculiarities and geographical distribution. 

384. General characters of the Rasores? 

385. Characters and examples of the Gallinaceous Birds ? 

386. Characters and examples of the Columbaceous Birds ? 

387. Mention an extinct Columbaceous Bird. 

. 388. General characters of the Scansores? 

389. Leading families of the Scansores? 

390. General characters of the Insessores? 

391. Mention the four sections into which the Insessores are divided, and 
state the peculiarities distinguishing these. 

392. Give examples of each of these sections. 

393. General characters of the Raptores ? 

394. Distinctions between Nocturnal and Diurnal Birds of Prey? 

395. Characters of the Saururoc? 


362 


QUESTIONS. 


396. For what bird has this order been established ? 

397. General characters of the Mammalia ? 

398. General structure of the backbone ? 

399. General number of cervical vertebras ? 

400. Distinction between “true” and “false” ribs? 

401. General structure of limbs ? 

402. What Mammals have no teeth ? 

403. What are the “ milk-teeth ? ” 

404. Describe the general groups of teeth in a Mammal. 

405. What is the “ diaphragm ? ” 

406. General structure of the heart and course of the circulation ? 

407. General structure of the lungs ? 

408. What is the “ corpus callosum ? ” 

409. What Mammals possess no external ear ? 

410. Mention some modifications of the integumentary appendages in 
Mammals. 

411. What Mammals are without hair when adult? 

412. What are the mammary glands? 

413. What is the “ placenta ? ” 

414. General characters of the Monotremata ? 

415. Mention the animals included in the Monotremata , and state their 
geographical distribution. 

416. What are the “ marsupial bones ? ” 

417. General characters of the Marsupialia? 

418. Geographical distribution of the Marsupials? 

419. Give examples of the Marsupials. 

420. General characters of the Edentata ? 

421. Geographical distribution of the order? 

422. Leading groups of the Edentata , and their distinguishing charac¬ 
ters ? 

423. General characters of the Sirenia ? 

424. Existing forms of the Sirenia? 

425. General characters of the Cetacea? 

426. Give examples of the Whalebone Whales and Toothed Whales. 

427. What is the “blowing” of a Whale ? 

428. What characters distinguish the Dolphins ? 

429. Nature of the tusk of the Narwhal ? 

430. General characters of the Ungulata? 

431. Divisions of Ungulata and their characters? 

432. Nature and position of the horns of Rhinoceros ? 

433. Characters and distribution of the Tapirs ? 

434. Characters, chief forms, and geographical distribution of the 
Equidce ? 

435. Characters and distribution of the Hippopotamus ? 

436. Characters of the Suida? Leading forms? 

437. General characters of the Ruminants ? 

438. Structure of the stomach in Ruminants ? 

439. Characters and distribution of Camelidce? 

440. Characters and distribution of Cervidce ? 

441. Nature of the horns of Cervidce? 

442. Characters and distribution of the Giraffe ? 

443. Characters and leading forms.of the Cavicomia? 

444. General characters and distribution of the Hgracoidea ? 

445. General characters and distribution of Proboscidea ? 


QUESTIONS. 


363 


446. Distinctions between the Indian and African Elephants ? 

447. General characters of the Carnivora? 

448. Sections into which the Carnivora are divided, and the characters 
of these ? 

449. Characters of the Seals ? 

450. Dentition of the Walrus? 

451. Characters of the Bears? 

452. Other Plantigrade Carnivora ? 

453. Characters and examples of the Mustelidce? 

454. Examples of the Melidce? 

455. Examples of the Viverridce? 

456. Characters and examples of the Canidce? 

457. Characters and distribution of Hycenidce? 

458. Characters and distribution of the Felidce? 

459. General characters of the Rodentia? 

460. Structure of the incisor teeth of Rodents ? 

461. Leading families of the Rodentia? 

462. General characters of the Cheiroptera ? 

463. What is the “ patagium ” of Bats ? 

464. Sections of the Cheiroptera , and their distribution 0 

465. General characters of the Insectivora ? 

466. Characters and examples of the Talpidce? 

467. Characters and examples of the Soricidce? 

468. Characters and examples of the Erinaceidce ? 

469. Other Insectivora ? 

470. Characters and distribution of the Flying-Lemurs ? 

471. General characters of the Quadrumana? 

472. Characters and distribution of the Strepsirhina ? 

473. Examples of Strepsirhina ? 

474. Characters and distribution of Platyrhina? 

475. Examples of Platyrhine Monkeys? 

476. Characters and distribution of Caiarhina? 

477. General characters of the Baboons ? 

478. Characters and examples of the Anthropoid Apes ? 

479. General characters of the order Bimana ? 




INDEX 


Acanthocephala , 109 ; general characters of, 
114. 

Acanthometra, 33, 39. 

Acanthophis, 245. 

Acanthopteri, 219. 

Acarina , 141. 

Achetina, 155. 

Acorn-shells, 136, 13 1 . 

Acrydium , 156. 

Actinia , 51, 86. 

Actinidce, 86. 

Actinozoa , 52, 53; general characters of, 84; 

orders of, 86-94. 

Adjutant, 269. 

Agouti, 311. 

Ailurus, 303. 

Air-receptacles of Birds. 261. 

Alcedinidce , 2T7. 

AZces, 301. 

AZcicZce, 267. 

Alcyonaria , 86; characters of, 90. 
Alcyonium, 90. 

Aifiree, 4. 

Alligator, 248. 

Alpaca, 301. 

Amblystoma , 223. 

Ainbulacral system of Echinus , 18, 99. 
Ameiva , 245. 

Ametabolic Insects, 150,153. 

Ammonites, 195. 

Amoeba, 30; nucleus of, 32; reproduction of, 
32. 

Amosbea, 30. 

Amphibia, 195, 205; general characters of, 
225; orders of, 226-233. 

Amphioxus, 214, 215. 

Amphipoda, 138. 

Anacanthini , 219. 

Analogy, 15. 

Anarthropoda , 119. 

Anatidce, 267. 

Anguitlula, 115. 

Anguis, 245, 246. 

Animals and plants, differences between. 3-6. 
Annelida, 119; general characters of, 120; 
typical segment of, 120; divisions of, 
121. 

Annuloida, 15; characters and divisions of, 
95. 

Annulosa, 15; general characters of, 118. 
Anomodontia, 237, 252. 

Anomura, 131. 


Anoplura, 153. 

Anoura, 226, 230, 232. 

Anserince, 267. 

Ant-eaters, 282, 286. 

Antelopes, 803. 

Antennae, 124, 139, 149. 

Anthropoid Apes, 317. 

Ant-lion, 156. 

Ants, 161, 162. 

Apes, 315, 817. 

Aphaniptera, 15S. 

Aphides, 154,155. 

Aphis-lion, 156,157. 

Aphrodite, 124,125. 

Apidce, 160. 

Aplacental Mammals, 286, 287. 

Aptera, 150. 

Apteryx, 270, 271. 

Apus, 138. 

Aquiferous system (Sponges), 41. 
Arachnactis, S6. 

Arachnida, 127; general characters of 139; 

orders of, 140-144. 

Araneida, 142. 

Archaeopteryx , 279. 

Arctomys, 312. 

Ardea, 269. 

Ardeidce, 269. 

Arenicola, 124,125. 

Argonauta, 190,191. 

Armadillos, 2S6. 

Arms, of Brachiopoda, 175; of Cephalo¬ 
poda, 188,190,191. 

Arthropoda, 119; general characters of, 126. 
Articulata, 126. 

Artiodactyla, 297, 298. 

Ascaris, 115, 

Ascidian Mollusks, 171; solitary, social, and 
compound, 173. 

A sinus, 298. 

Ass, 298. 

Asteroidea, 96; general characters of, 100, 

101 . 

Atolls, 89. 90. 

Atrium (Tunicata), 173. 

Auchenia , 301. 

Aurelia, 80. 

Aves, 205; general characters of, 253; feath¬ 
ers of, 253; vertebral column of, 254; beak 
of. 255; pectoral arch of, 255; hind-limb of, 
257; foot of, 258; digestive system of. 258; 
respiratory system of, 260; circulatory 





IXDEX. 


365 


system of, 261; nervous system and organs 
of sense of, 262, 263; orders of, 265. 
Axolotl, 227, 228. 

Aye-Aye, 316. 

Baboon, 317. 

Babyroussa, 299. 

Badger, 308. 

BaUzna , 295. 

Balcenidce , 295. 

Balancers, 158. 

Balanidat , 137. 

Balanus , 137. 

Bald Eagle, 278. 

Baleen, 295. 

Balistidce, 220. 

Bandicoot, 291. 

Banxring, 315. 

Bascanion , 244. 

Bcitides , 223. 

Batrachia , 230. 

Bats, 312, 813. 

Beaver, 811. 

Bee-eaters, 277. 

Bees, 160. 

Bslemnites, 192. 

Big-born, 303. 

Bimana , 2S7; general characters of, 319. 
Biology, definition of, 3. 

Bird-lice, 153. 

Birds (see Aves). 

Bird’e-head process, 171. 

Birds of Prey, 277. 

Bison , 303. 

Bittern, 269. 

Bivalve Shell-fish, 167, 176. 

Black-game, 272. 

Black Snake, 244. 

Bladder-worms (see Cystic Worms). 
Blastoidea , 105. 

Blattvna , 155. 

Blind-worm, 245, 246. 

Boa, 244. 

Bombyx , 160. 

Bonasa , 272. 

Book-scorpion, 139. 

Bos, 303. 

Bov idee, 803. 

Box-tortoise, 240. 

Brachiopoda , 165, 167; general characters 
of, 174, 175. 

Bracliyura , 132. 

Bracts (Oceanic Hydrosoa ), 71. 
Bradypodidce , 292. 

Branchial hearts (’Cuttle-fishes). 189. 
Branchial sac (Tunicata), 172; (Lancelet,), 
215. 

Branchiate Gasteropods, 182. 

Bubalus , 303. 

Buccinum , 183. 

Bitceridce , 276. 

Buffalo, 303. 

Bvfonidce , 232. 

Bullfinch. 276. 

Bunting, 276. 

Bustards, 269. 

Butterflies, 148, 159. 

Byssus (of Lamellibranchiata ), 177. 

Caducibranchiata (Amphibia), 227, 229. 
Caeca, intestinal (of Birds), 260. 


Ccecilia , 226, 227. 

Caiman, 248. 

Calamaries, 187, 190, 192. 

Calycophoridce , 70-72. 

Camelidce , 301. 

Camelopardalidce , 302. 

Campanularida , 68; medusiform gono- 
phores of, 69. 

Canals, of Sponges, 41; of Alcyonaria , 90; 

of Ctenophora , 94. 

Canidce , 308. 

Cantharis , 163. 

Capreolus , 302. 

Caprimulgidce, 277. 

Capybara, 311. 

Caribou, 302. 

Carinaria , 184,185. 

Carnivora , 287; general characters of, 303. 
Carriage-spring apparatus ( Brachiopoda\ 
175. 

Cassowary, 269, 271. 

Casuarius , 271. 

Castoridc e, 311. 

Catarhina , 316. 

Cathartes , 278. 

Cats, 806, 309. 

Cavidce , 811. 

Cavicornia , 302. 

Cebidce , 316. 

Cellulose in Ascidians, 5, 172. 

Centetes, 315. 

Centipedes, 144,145. 

Ceplialaspis , 222. 

Cephalopoda , 165, 176; general characters 
of, 187; respiratory organs of, 189; shell 
of, 190; reproduction of, 189. 
Cephalothorax, 128, 139. 

Cerastes , 245. 

Certhidce , 276. 

Cervidae , 301. 

Cervus , 302. 

Cestraphori, 223. 

Cestum , 94. 

Cetacea , 287; general characters of, 294. 
Chatognatha , 119. 

Chameleo , 247. 

Chamois, 303. 

Charadriidce , 269. 

Cheiromys , 316. 

(7 heiroptera , 287; general characters o£ 
312. 

Cheirotherium, 233. 

Chelae, 131. 

Chelydra , 240. 

Chelifer , 142. 

Chelonia , 237; general characters of, 238. 
Chimoera , 222, 223. 

Chimpanzee, 318. 

Chitine, 61. 

Chlamyphorus, 292. 

Chlorophyll, in Animals, 5. 

Chrysochlori8, 314. 

Cicada, 154. 

Ciliata ( Infusoria ), 49. 

Cirripedia , 136. 

Cistudo , 240. 

Civet, 308. 

Cladocera , 135,136. 

Clamatores , 273. 

Classification, 6, 14. 

Cleodora , 186. 



366 


INDEX. 


(Mona, 43. 

Cloaca, of Rotifera, 117; of Insects, 149; of 
Amphibia, 225; of Reptiles, 236; of Birds, 
260; of Monotremes, 288. 

Clupeidce, 219. 

Coati, 308. 

Cochineal Insects, 154. 

Cockroaches, 155. 

Cocoon, 152. 

Ccelenterata, 15; general characters of, 50- 
52; thread-cells of; 52; divisions of, 52. 
Ccenosarc, 56. 

Coleoptera , 162, 163. 

Collosphcera , 39, 40. 

Colobus, 317. 

Coluber, 244. 

Columbacei, 271-273 
Comatula , 104,105. 

Condor, 279. 

Condylura, 314. 

Conirostres, 276. 

Contractile vesicle, of Protozoa, 26; of Amoe¬ 
ba, 31; of Infusoria, 47. 

Coot, 269. 

Copepoda, 135, 136. 

Copperhead Snake, 244. 

Coral, 88. 

Corallite, 88. 

Cor allium, 91. 

Corallum, 86, 88. 

Coral-reefs, 88, 89. 

Cordylophora, 60, 62. 

Corncrake, 269. 

Corynida, 57; general characters of, 60, 61; 

reproduction of, 62, 63. 

Coryomorpha, 62. 

Coturnix, 272. 

Craddae , 272. 

Crane, 269. 

Crane-fly, 158. 

Craspeda, 87. 

Cribella, 100,101. 

Crinoidea, 96; general characters of; 103- 
105. 

Cristatella , 171. 

Crocodilia, 237; general characters of, 247, 
248. 

Crop, of Insects, 148; of Birds, 260. 
Cross-bill, 276. 

Crotalidae, 244. 

Cro talus, 244. 

Crow, 276. 

Crustacea, 127; general characters of 128. 
Ctenophora , 85; general characters of, 93, 94. 
Ctenophores, 93. 

Cuckoo, 273. 

Cuculidcc, 273. 

Culex, 159. 

Curassow, 272. 

Curlew, 269. 

Cursores, 265, 269. 

Cuticle, of Infusoria , 46. 

Cuttle-fishes,' 166,187-190. 

Cuvieria, 186. 

Cyamus, 138. 

Cyanea, 80. 

Cyclas, 178. 

Cyclolabridce, 219. 

Cyclops , 136. 

Cydippe, 93. 

Cygnidce, 267. 


Cynthia , 172. 

Cyprinidae, 219. 

Cypris, 136. 

Cypselidce, 277. 

Cystic Worms, 109, 111, 112. 

Cystoidea, 96,105. 

Daphnia, 136. 

Dasypodidw, 292. 

Dasyprocta, 311. 

Dasyurus, 291. 

Decapoda ( Crustacea ), 129; {Cephalo¬ 
poda), 191, 192. 

Deer, 301. 

Deinosauria, 237, 252. 

Delphinidce, 296. 

Dental formula, 2S3. 

Dentirostres, 276. 

Desmidice, 5. 

Diatom acece, 5. 

Dibranchiata, 189,190,192. 

Dicotyles, 299. 

Didelphida >, 290, 291. 

Didelphys , 291. 

Difflugia, 32, 36. 

Digitigrada, 306, 308. 

Diphyes, 71. 

Dipnoi, 214; general characters of 223. 
Dipodidce, 811. 

Diptera, 158. 

Discophora (Medusa), 57, 74, 75, 77. 
Discorbina, 33-35. 

Di stoma, 112. 

Diver, 267. 

Dodo, 273. 

Dog, 308. 

Dolphin, 296. 

Doris, 184. 

Dormice, 811. 

Dorsal vessel of Insects, 149. 

Draco, 246, 251. 

Dragon-flies, 156. 

Dromaius, 270. 

Dromedary, 301. 

Duck, 267. 

Duck-mole, 2S8. 

Dugong, 293, 294. 

Eagle, 278. 

Echidna, 2S8, 2S9. 

Echinodeimata, 95; general characters of, 
96. 

Echinoidea, 96; general characters of, 97; 
aquiferous system of, 98; development of, 
100 . 

Echinorhynchus, 114. 

Echinus, anatomy of, 97-99. 

Ectocyst, 168. 

Ectoderm, 50, 52, 84. 

Edentata, general characters of, 291. 

Egret, 269. 

Elaps, 245. 

Elasmobranchii, 214; general characters of 
221 ;• sub-orders of, 223. 

Elephant, 304, 305. 

Elephant-shrew, 314. 

Elk, 301. 

Elytra, 163. 

Emeu, 270. 

Emydidce, 240. 

Emys, 239. 




INDEX. 


367 


Endocyst, 168. 

Endoderm, 50, 52, 84. 

Entozoa, 108. 

Eozoon , 37. 

Ephemeridre , 156. 

Epistylis , 46, 48. 

Equidce, 298. 

Erinaceidce , 314. 

Erinaceus, 315. 

Ermine, 308. 

Errantia , 121,124. 

Esocidce, 219. 

Eudendrium , 61. 

Euplectella , 42. 

Eurypterida, 134. 

Eyes of Insects, 149. 

Feather-star, 104. 

Felidee, 306, 309. 

Field-bug, 154. 

Filaria, 115. 

Finches, 276. 

Finner-whales, 295. 

Fission, continuous and discontinuous, 54. 
Fissirostres, 276. 

Flngellata ( Infusoria ), 49. 

Fleas, 158. 

Flesh-flies. 159. 

Float, of Physophoridce , 72. 

Flukes, 112. 

Flustra , 4,170. 

Fly-catcher, 276. 

Flying dragon, 246. 

Flying-lemur, 315. 

Flying squirrel, 311. 

Food of animals and plants, 5, 6. 
Food-vacuoles, 47. 

Foot, of Mollmca , 166,177,181, 184,186,187. 
Foot-jaws, 130. 

Foot-tubercles, 120. 

Foraminifera , 26,29,30; general characters 
of, 33; pseudopodia of, 33; shell of, 34; af¬ 
finities of, 36; distribution of, in space, 37; 
in time, 37; presence of, in white chalk, 
37. 

Forest-flies, 159. • 

Formica , 162. 

Formicidie , 160. 

Fowl, 272. 

Fox-bats, 313. 

Frigate-birds, 267. 

FHngiUidce , 276. 

Fringing-reefs, 89. 

Frog. 230, 232; development of, 231. 

Fulica , 269. 

Funnel, of Ctenophora , 94; of Cephalopo¬ 
da , 188; of Nautilus , 188, 192. 

Gad-flies, 159. 

Gad idee, 219. 

Galeopithecus , 315. 

Gallinacei, 271. 

Gallinula . 269. 

Gallus, 272. 

Gammarus , 138. 

Gannet, 261. 267. 

Ganoidei , 214; general characters of, 220. 
Gasteropoda , 165, 176; general characters 
of, 180; shell of, 182 ; odontophore of, 181; 
development of, 182. 

Gavial, 248. 


Geckotidce , 246. 

Geese, 267. 

Gemitores , 273. 

Gemmation, continuous and discontinuous. 
54. 

Gemmules of Spongilla , 43. 

Gemsbok, 303. 

Generations, alternation of, 64, 65. 

Genette, 308. 

Gephyrea , 119. 

Gibbon, 318. 

Giraffe, 302. 

Gizzard, of Insects, 148; of Birds, 260. 
Glass-snake, 245. 

Glohigerina , 34, 36. 

Glutton, 808. 

Gnats, 159. 

Gnu, 303. 

Goat, 303. 

Goat-sucker, 277. 

Gobiidce. 219. 

Golden mole, 311. 

Goniaster, 101. 

Gonophores, 63, 64; medusiform, 65, 68. 
Gonosome, 63. 

Gordiacea , 109; characters of, 114. 
Gorgonidce , 91, 92. 

Gorilla, 318, 319. 

Grallatores, 265, 267. 

Graptolitidce, , 82. 

Grasshoppers, 155. 

Grebe, 267. 

Greenland Whale, 295. 

Gregarina , 28. 

Gregarinidce , 27; reproduction of, 28. 
Grosbeak, 276. 

Gruidce, 269. 

Gryllina , 155. 

Guan, 273. 

Guillemot, 267. 

Guinea-fowl, 272. 

Guinea-pig, 311. 

Guinea-worm, 115. 

308. 

ITaemoptds. 122. 

Ilag-fishes, 216. 

Hair-worms. 114. 

Ilalicore , 293, 294. 

Ilalietus , 278. 

Ilalteres (see Balancers). 

Hamster. 310. 311. 

Tlapaliclce , 316. 

Hare, 311. 

Harlequin Snake, 245. 

Harvest Spiders, 142. 

Hawks, 277, 278. 

Hectocotylus. 190. 

Hedgehog, 315. 

Hemelytra, 154. 

Hemimetabolic Insects, 150, 154. 

ITemiptera. 154. 

Hermit-crabs. 131. 

Heron, 268, 269. 

Ileteropoda , 184. 

Ilippobosca , 159. 

Hippocampidce , 220. 

IUrudinea , 121; general characters of, 121, 
122. 

Tlirundinidoe , 277. 

Holocephali , 223. 



368 


INDEX. 


Holometabolic Insects, 150,15S. 
Ilolothuroidea , 96; general characters of, 
106. 

Homology, 14,15. 

Honey-badger, 308. 

Honey-eater, 276. 

Hoopoe, 276. 

Horn bill. 261, 276. . 

Horse, 298. 

Horseshoe Crab, 133, 134. 

House-fly, 159. 

Humming-birds, 276. 

Ilycenidoe , 309. 

Hydatids, 112. 

Ilydatina, 116. 

Hydra, 53, 56-59; reproduction of, 60. 
Ilydrachna, 141. 

Hydra-tuba, 80. 

Hydrida , 57. 

Ilydroida, 57, 66; reproduction of, 62-66. 
Hydroid Zoophytes, 53, 59. 

Ilydrophidce , 244. 

Hydrosoma, 56. 

Hydrotheca, 66, 67. 

Hydrozoa , characters of, 52,53; terminology 
of, 53, 56; reproduction of, 62, 66; divis¬ 
ions of, 57. 

Ilylobates , 318. 

Ilymenoptera , 160. 

Hyracoidea, 287; general characters of, 303. 
llyrax , 304. 

Hystricidoe , 311. 

Ibis, 269. 

Ichneumon, 160. 

Ichthyomorpha , 227. 

1chthyophthira , 138. 

Ichthyopsida, 204. 

Ichthyopterygia , 237; characters of, 249. 
Ichthyosaurus , 249. 

Iguana, 246. 

Ilyanthus , 87. 

Imago, 150,151. 

Imperforata ( Foraminifera), 35. 
Individual, definition of, 53-55. 

Infusoria , 27, 45; general characters of, 46; 

distribution of, in space, 49. 

Insecta, 127; general characters of, 146; or¬ 
gans of the mouth of, 147; digestive sys¬ 
tem of, 148; metamorphoses of, 150; orders 
of, 153-163. 

Insectivora, 287; general characters of. 313, 
314. 

Insessores , 265, 274. 

Invertebrata , general characters of, 15, 16, 
196. 

Isis, 91, 92. 

Isopoda, 133. 
lulus, 145. 

Jaguar. 309. 

Jelly-fishes, 64, 65, 74. 

Jerboa, 311. 

Jumping-mouse, 311. 

Jungle-fowl, 272. 

Kangaroo, 290. 291. 

Kangaroo-bear, 290, 291. 

King-crab, 133,134. 

Koodoo, 303. 


Labium, 148. 

Labrum, 147. 

Labyrinthodontia , 226, 232. 

Lacerta, 245. 

Lacertilia, 237; general characters of, 245. 
Lcemodipoda, 138. 

Lagena, 34, 35. 

Lagopus, 272. 

Lamellibranchiata, 165, 174; general char¬ 
acters of, 176; shell of, 178; respiration of, 
179; habits of 180. 

Lamprey, 216, 217. 

Lamp-shells, 167, 174. 

Lancelet, 197, 203, 204, 212. 

Land-salamanders, 229, 230. 

Laniidce, 276. 

Lapwing, 269. 

Laridw, 267. 

Larks, 276. 

Larva (of Insects), 150, 151. 

Leeches, 121, 122. 

Lemming, 311. 

Lemurs, 316. 

Leopard, 309. 

Lepadidcp, 137. 

Lepidoptera, 159. 

Lepidosiren, 212, 213, 216, 223, 224. 
Lepidosteus, 220. 

Leporidce , 311. 

Lernoea, 138. 

Libellulidoe , 156. 

Lice, 153. 

Limulus, 134. 

Lingual ribbon (of Mollusca ), 181, 1S2. 
Lingula, 174, 175. 

Lion, 309. 

Liver-fluke, 112. 

Lizards, 245. 

Lobster, 129,130. 

Lob-worm, 124, 125. 

Locustidai, 155. 

Lopliobranchii, 220. 

Lophopus, 170. 

Lophortyx, 272. 

Lories, 274. 

Lucernaria, 78. 

Lucernarida, characters of, 78; develop¬ 
ment of, 79. 80; structure of reproductive 
zooids of, 80-82. 

Lumbricidce, 122. 

Lumbricus, 123. 

Lynx, 309. 

Macaque, 317. 

Maccaw, 274. 

Macropodidce, 290. 

Macroscelides, 314. 

Macrura, 129. 

Madreporiform tubercle, of Echinus, 98; of 
Star-fishes, 101; of Holothurians, 106. 
Malacodermata ( Zoantharia), 86. 
Malacopteri, 219. 

Mallophaga, 153. 

Malpighian vessels, of Insects, 149. 
Mammalia, 205: general characters of, 280; 
skeleton of. 281; teeth of, 282; digestive 
system of, 201; circulatory system of, 284; 
respiratory system of, 285, nervous system 
of, 285; integumentary system of, 2S6; 
orders of, 287. 

Mammoth, 305. 






INDEX. 


369 


Manatee, 298. 

Mania, 286. 

Mantle, 167,175,176, 179,188. 

Manubrium, 64, 65, 68, 76. 

Marginal bodies, of Medusidce, 76; of Lu- 
cernarida , 81. 

Marmoset, 815. 

Marmot, 812. 

Marsipobra nehii, 214; characters of, 216. 
Marmpialia , 2S7; characters of 289. 
Marten, 277. 

May-flies, 156. 

Measles, of pig. 111. 

Medusce, naked-eyed, 74, 76; hidden-eyed, 
74,81. 

Medusidce , 74, 75. 

Medusoid buds, of Ilydrozoa , 64, 65, 68, 76. 
Megapodidce , 272. 

Meleagris , 272. 

Meles , 808. 

MeUcerta , 116. 

Meliphagidce , 276. 

Mephitis , 808. 

Meropidce , 277. 

Merosiomata , 138. 

Memlidae , 276. 

Mesenteries, of Actinozoa , 84, 87. 
Metamorphoses of Insects, 150,151. 

Mice, 311. 

Miliola , 33, 84, 37. 

Millipedes, 144,145. 

Mink, SOS. 

Mites, 141. 

Modeeria , 75. 

Mole, 314. 

Mollusca, 15; general characters of, 164; 

shell of, 166; divisions of, 167. 

Mollusca Proper , characters of, 167; di¬ 
visions of, 176-194. 

Molluscoida , characters of, 167; divisions 
of, 168-175. 

Monera , 29. 

Monitors, 246. 

Monkeys, 315. 

Monothalamous shells ( Foraminifera'), 85. 
Monotremata , 287; characters of 288. 
Moose, 301. 

Morphology, 10. 

Morse, 307. 

Moths, 159,160. 

Mound-birds, 272. 

Mugilidce, 219. 

Multivalve shells, 167, 182. 

Muranidce , 219. 

Muridce , 311. 

Musca , 159. 

Muscicapidne , 276. 

Musk-ox, 304. 

Musquash, 311. 

Mustelidce. 308. 

J/?/a, 177. 180. 

Mycetes , 316. 

Myoxidce . 311. 

Myriapoda , 127; general characters of 144. 
Myrmecophaga , 292. 

Myrmeleo , 156. 

Myxine , 216. 

Myxinidce, 216. 

Myxinoids, 213, 216, 224. 

Maididce, 122,123. 


May a, 244, 245. 

Narwhal, 296. 

Nasua , 308. 

Natatores , 265; characters of, 266. 

Nautiloid shells ( Foraminifera ), 36. 
Nautilus, Pearly, 187-190, 192, 193; Paper, 
187, 188, 190, 191. 

Nectocalyces, 70, 71. 

Nematoda , 109; general characters of, 114. 
Nemertidae , 113. 

Nervures, 146. 

Neuroptera , 156. 

Night-heron, 269. 

Moctiluca, 49. 

Modosaria , 34, 35. 

Nucleolus, of Paramcecium, 47. 

Nucleus, of Protozoa, 26; of Amoeba, 32; 

of Paramcecium , 47. 

Nudibranchiata, 184. 

Mumenius , 269. 

Nivmida, 272. 

Nummulites, 37, 38. 

Nummulitic Limestone, 37. 

Nycticebidoe , 316. 

Oceanic Hydrozoa , 70. 

Octopoda , 188,191. 

Octopus , 191. 

Odontoceti , 295. 

Odontophore, 165,181, 186, 188. 

Oligochceta, 121; characters of, 122. 
Omnivora ( Ungulata ), 298. 

Oniscus , 133. 

Operculum (of Mollusks), 181; (of Fishes), 
211 .. 

Ophidia , 237; characters of, 241-244. 
Ophiocoma , 102. 

Ophiomorpha, 226. 

Ophisaurus , 245. 

Ophiura , 102. 

Ophiuroidea , 96; characters of, 101-103. 
Opossum, 290, 291. 

Orang-outan, 318. 

Organ-pipe Coral, 91. 

Organs of the mouth of Insects, 147. 
Ornithorhynchus, 288, 2s9. 

Ortlioceras , 193,194. 

Orthoptera , 155. 

Ortyx, 272. 

Orycteropus, 293. 

Oscula, of Sponges, 41, 42. 

Osteolepis. 221. 

Ostraciontida , 220. 

Ostracocla , 135,136. 

Ostrich. 254, 258, 269, 270. 

Otidce , 269. 

Otter, 308. 

Ovarian vesicles, of Sertularida, 68. 

Oribos, 303. 

Ovidce, 303. 

Ovipositor, 147, 160. 

Oris, 303. 

Owls, 278. 

Oxen, 303. 

Oxyuris, 115. 

Oyster-catcher, 269. 

Paca, 311. 

Paguridce , 131. 

Pallial line, 178. 179. 

Pallial sinus, 179. 



370 


INDEX. 


Pallium (see Mantle). 

Pangolin, 293. 

Paper Nautilus, 1S7,18S, 190,191. 
Paramecium, 46, 47. 

Parapodia, 120. 

Farida, 276. 

Parrakeets, 274. 

Parrots, 259, 273. 

Partridge, 272. 

Passerine Birds, 274. 

Patagium, 312. 

Pauropus , 145. 

Pa/oo , 272. 

Pea-fowl, 272. 

Pearly Nautilus, 1S7-190,192,193. 

Peccary, 299. 

Pecten , 180. 

Pedicellariae, of Echinus , 98; of Star-fishes, 
101. 

Pedipalpi , 141. 

Pelias, 244. 

Pelicanus , 267. 

Peltogaster , 138. 

Penguin, 266, 267. 

Pennatula , 91. 

Pentatoma , 154. 

Perameles , 291. 

Perchers, 274. 

Percidm, 219. 

Perdicidce , 272 

Perennibranchiata (Amphibia), 227. 
Perforata (Foraminifera), 35. 
Perissodactyla, 297. 

Petromyzon, 217. 

Petromyzonidce , 216. 

Phacochcerus, 299. 

Phalacrocorax, 267. 

Phalangers. 291. 

Phalangida, 142. 

Phalangista, 291. 

Pharyngobranchii, 214. 

Pharynx (of Ascidians), 174; of Lancelet, 
215. 

Phascolarctos, 290, 291. 

Pliasianidae, 272. 

Pheasants, 272. 

Pholades, 180. 

Phryganeidce, 156. 

Phyllopoda, 138. 

Phyllostomida’, 812. 

Physalia, 53, 72. 

Physiology, 10. 

Physophorida, 72. 

Picidoe, 273. 

Pigeons, 271-273. 

Pinnigrada, 306, 307. 

Pipidce, 232. 

Pisces, 204; general characters of, 206; 
scales of, 206; skeleton of, 207; limbs of, 
208; tail of, 210; digestive system of, 210; 
respiratory system of, 211; heart of, 212; 
swim-bladder of, 213; nervous system of, 
213; reproduction of, 213; orders of, 214- 
224. 

Placental Mammals, 2S6, 287. 

Plagiostomi , 223. 

Planarida, 113. 

Plantigrada, 306, 308. 

Platyrhina, 315. 

Plectognathi, 220. 

Plesiosaurus, 250. 


Pleurobrachia, 93. 

Pleuronectidce, 219. 

Pluteus, 100. 

Pneumatophore. 72. 

Podosomata, 140. 

Podura, 154. 

Pole-cat, 308. 

Polycystina, 36; characters of, 38. 
Polygastrica, 47. 

Polynoe, 125. 

Polypary, 56. 

Polype, 85. 

Polypide, 168. 

Polypidom, 56. 

Polypi te, 56. 

Polypterus, 220, 221. 

Polythalamia (Foraminifera ), 35. 
Polyzoa, 165, 167; characters of, 168-171. 
Porcupine, 286. 

Pores, of Sponges, 41, 42, 

Porpoise, 296. 

Portuguese Man-of-war, 53,72. 

Poulpes, 191. 

Prairie-dog, 312. 

Proboscidea, 287; characters of, 304. 
Procellaridce, 267. 

Procyon, 308. 

Prong-buck, 303. 

Proteus, 227, 228. 

Proteus-animalcule, 30. 

Protophyta, 4. 

Protoplasm, 3. 

Protozoa, 4,15; characters of, 25-27; classi¬ 
fication of, 27. 

Proventriculus of Birds, 260. 

Pseudohaeraal System, 121. 

Pseudo-hearts. 175. 

Pseudonavicellae, 28. 

Pseudopodia, of Protozoa, 27: of Rhizopo • 
da, 29; ot Amoeba, 30; of Foraminifera, 
33; of Radiolaria, 38. 

Psittacidce, 273. 

Ptarmigan, 272. 

Pterodactyles, 251. 

Pteropida, 313. 

Pteropoda, 166; characters of, 1S6. 
Pteropus, 313. 

Pterosauria, 237; characters of, 250. 
Pterygotus, 134. 

Pulicidce , 158. 

Pulmonary sacs ( Arachnida ), 140. 
Pulmonate Gasteropoda, 182,185. 

Puma, 309. 

Pupa, 150,151. 

Pycnogonum, 141. 

Python, 235, 244. 

Quadrumana, 287; characters of, 315. 
Quagga. 298. 

Quail, 272. 

Babbit, 311. 

Baccoon, 308. 

Radiata, 50. 

Radiol ana, 29; characters of, 38,39. 

Bail, 269. 

Rallidce, 269. 

Ranidce, 232. 

Raptores, 266; characters of. 276. 

Rasores, 265; characters of 271. 

Bat, 311. 




INDEX. 


371 


Rattlesnake, 244. 

Red Coral, 92. 

Red Deer, 302. 

Jiegnum Protisticum , 4. 

Reindeer, SOI. 

Reproduction, general features of, 53, 54; in 
Hydroid Zoophytes, 62-66. 

Replilia, 205; characters of, 234: jaw of, 
235; teeth of, 235; circulation of, 236; res¬ 
piration of, 237; orders of, 237. 

Respiratory tree, of Ilolotliurians, 107. 
Respiratory tubes, of Rotifera , 117. 

Rhea , 269, 270. 

Rhinoceros , 297, 298. 

Rhisocephala , 138. 

Rhizocrinus , 104, 105. 

Rhizopoda , 27; characters of, 29; divisions 
of, 29. 

Rhizostoma , 82. 

Rhizostomidce, 82. 

Rhytina , 294. 

Ribbon-worms, 113. 

Rodentia , 2S7; characters of, 309, 310. 
Roe-buck, 302. 

Rorqual, 295. 

Rolifera, 109; characters of 115. 
Round-worms, 114. 

Ruffed Grouse, 272. 

Ragosa, 92. 

Ruminantia , 298, 299; dentition of, 299; 
stomach of, 300; families of 801. 

Sable, 308. 

Sagitta, 119. 

Salmonidce , 219. 

Sandpipers, 269. 

Sanguisuga , 122. 

Sarcode, 26. 

Sarcoids, of Sponges, 41. 

Sarcorhampus , 279. 

Sauropsida , 205. 

Sauropterygia , 237; characters of, 250. 
Saururce , 266, 280. 

Saw-flies, 160. 

Scalops , 314. 

/S 'cansores, 265; characters of, 273. 
iScincus, 246, 247. 

Sciuridce, 811. 

Sclerobasica (Zoantharia), 90. 

Sclerobasic Corals, 88, 91, 92. 

/Sclerodermata ( Zoantharia ), 87. 
Sclerodermic Corals, 88, 91, 92. 

Scolecida, 95; characters of, 108. 
Scolopacidce , 269, 

Scolopendra , 145. 

Scomberida ’, 219. 

Scorpion, 141,142. 

Sea-anemones, 86. 

Sea-cucumbers, 106. 

Seals, 306, 307. 

Sea-mosses, 167,168. 

Sea-mouse. 124,125. 

Sea-slugs, 184. 

Sea-spiders, 140. 

Sea-squirts, 165,171. 

Segmental organs of Annelides, 121. 

Seiachii , 223. 

Semnopithecus, 316. 

Serpula, 123,124. 

Sertularida , 57, 61; characters of 66; poly- 
pites of, 66; reproduction of, 67. 


Sheep, 303. 

Shell, of Foraminifera , 34; of Mollusca, 
166, of Brachiopoda, 174; of Lamelli- 
branddata, 178; of Gasteropoda, 182; of 
Iteteropoda , 1S5; of Pteropoda , 186; of 
the Argonaut, 190,191; of Pearly Nautilus, 
190,192. 

Shrew-mice, 814. 

Silk-moth, 160. 

Siluridce , 219. 

Simia, 318. 

Siphonophora , 57.; characters of, 70. 
Siphons, of Lumellibranchiata , 174,179. 
Sipunculus, 120. 

Nireri, 227, 228. 

Sircnia, 287; characters of, 293. 

Slunk, 246, 247. 

Skunk, 308. 

Sloths, 292. 

Slow-worm, 215. 

Snakes, 201. 235. 

Snapping-turtle, 240. 

Snipes, 269. 

Soft-tortoises, 240. 

Soiaster , 101. 

Slien, 180. 

Somatic cavity, of Co&ienterata, 51,84. 

Surer, 314. 

Soricidce , 314. 

Spatularia , 221. 

Sperm-whale, 295. 

Spheniscida>, 267. 

Spider-monkevs, 316. 

Spiders, 139, 140, 142. 

Spinneret, of Spiders, 143; of Caterpillars, 
159. 

Spirorbis , 124. 

Spongida, 29 ; characters of, 36; aquiferous 
system of, 41; reproduction of 43; dis¬ 
tribution of, in space, 43. 

Spongilla , 42; reproduction of, 43. 
Spoon-bill, 269. 

Spoon-worm, 120. 

Spring-bok, 303. 4# 

Spring-tails, 153. 

Squids, 187, 190, 192. 

Squilla, 138. 

Squirrel, 311. 

Star-nosed Mole, 314. 

Stentor, 5, 48, 49. 

Stephanoceros , 116. 

Stomapoda , 138. 

Storks, 269. ( 

Strepsirhina, 316. 

Strep8iptera, 162. 

Strigidce , 278. 

Struthio, 270. 

Sturgeon, 220, 221. 

Sturio, 220. 

Sturionidce, 221. 

Sub-kingdoms. 11.15. 

Suctoria ( Infusoria ), 49. 

267. 

Surinam Toad, 232. 

Nws, 299. 

Swallows. 277. 

Swifts, 258, 277. 

Swim-bladder, of Fishes, 213. 
Swimming-bells, 70, 71. 

Syngnathidue , 220. 

Syrinx, 120. 



372 


INDEX. 


Tabanidce , 159. 

Tania , 109, 111. 

Tceniada, 108; characters of, 109; develop¬ 
ment of, 110, 111. 

Talitrus , 138. 

Talpidce, 314. 

Tanagers, 276. 

Tantalince , 269. 

Tape-worm, 109-111. 

Tapir, 297. 

Teleostei, characters of, 217-219; sub-orders 
of, 219, 220. 

Tenrec, 315. 

Te n tkredinidcc. 160. 

Termites, 156, 157. 

Terrapin, 240. 

Test, of Foraminifera, 34; of Echinoidea, 
97; of Tunicata, 172. 

Testudo , 241. 

Tetrabranchiata , 189,192,193. 
Tetranychus, 141. 

Tetrao, 272. 

Tetraonidcc, 272. 

Thalassicolla , 39, 40. 

Thalassicoliida, 89. 

Theriomorpha, 230. 

Thick-knee, 269. 

Thread-cells, 52. 

Thread-worms, 114. 

Thylacinus, 291. 

Thysanura , 153. 

Ticks, 140, 141. 

Tiger, 309. 

Tipula , 158. 

Tits, 276. 

Toads, 230-232. 

Tongue, of Gasteropods, 181; of Cuttle-fish¬ 
es, 188; of Snakes, 242; of Birds, 259. 
Tortoises, 235, 236, 238, 240. 

Tracheae, 140, 149. 

Tree-frog, 230, 232. 

Trematoda , 108; characters of, 112. 
Trichecus, 307. 

Trichina , 115. 

Trigonocephalus, 244. 

Trilobita, 135. 

Tringidce , 269. 

Trionycidce, 240. 

Triton , 229. 

Trochilidce. 276. 

Troglodytes, 318. 

Trogonidce , 274. 

Trophosome, 63. 

Tube-feet of Echinus , 98, 99. 

Tubicola , 121, 123. 

Tubifex , 123. 

Tnbipora , 91. 

Tubularia , 61. 

Tubvlarida (see Corynida). 

Tunicata. 165,167; characters of, 171,172. 
Tupaia , 315. 

Turbellaria , 108; characters o£ 113. 


Turkey, 272. 

Turn-stone, 269. 

Turritella , 183. 

Turtles, 235, 236, 238, 239. 

Umbo, 178. 

Umbrella, of Lucemarida , 78, 80-82. 
Univalve Shells, 167,180, 182. 

Ungulata , 287; characters of, 296. 

Vpupina 276. 

Ur aster, 101. 

Urodela , 226, 227. 

Ursidce, 308. 

Vacuoles, of 31; of Paramcecium , 

47. 

Taginicola , 48, 49. 

Valkeria , 170. 

Vampire-bats. 313. 

Varanidce , 246. 

Veil, of gonophores, 64, 68; of nectocalyces, 
71; of naked-eyed Medusa , 76. 

72. 73. 

Venus's Flower-basket, 42. 

Venus’s Girdle, 94. 

Uer»?e,s, 119. 

Vertebra, structure of, 197, 198. 

Vertebrata, 195; general characters of, 195; 
skeleton of, 197-201; digestive system of, 
201; blood of, 202; respiration of, 203; 
nervous system of, 204; reproduction of 
204; divisions of, 204. 205. 

Vesicle, contractile, of Protozoa , 26. 
Vespidce , 160. 

Viperidce , 244. 

Virgularia , 90. 

Vixerridce, 308. 

Vorticella , 4S, 49. 

Vulture, 278. 

Wah, 308. 

Walrus, 307. 

Wapiti, 302. 

W T arblers. 276. 

Wasps, 160. 

Water-hens, 269. ‘ 

Water-vascular system, 95, 96. 

Weasel, 308. 

Wolf, 308. 

Wolverine, 308. 

Woodcock, 269. 

Woodpeckers, 273. 

Wren, 276. 

Xiphosura, 133. 

Zebra, 298. 

Zoantharia, 86; Malacodermata. 86; 

robasica. 90; sclerodermata , 87. 
Zoanthus , 87. 

Zobid, 55. 

Zoology, definition of, 3. 




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